Parasagittal Cuts Research Articles

Upper eyelid lymphatic anatomy is associated with blepharoplasty recovery

BackgroundLymphatic vessels support wound recovery and absorb excess fluid. Blepharoplasty involves excess tissue excision, and the present study investigated the relationship between the lymph vessel density of excised tissue and the postoperative course. MethodsForty eyelids from 21 blepharoptosis patients who underwent blepharoplasty were enrolled. Each resected excess tissue sample was divided into four parts by three parasagittal cuts—medial, central, and lateral—and the area percentages occupied by lymphatic vessels and elastic fibers in the cut-exposed inner tissue between skin and muscle were determined by histology. The wound healing process was assessed at 2 weeks and 1, 3, and 6 months postoperatively, by using a visual analogue scale (VAS) for estimating edema and the Vancouver Scar Scale (VSS). ResultsWith increasing age, the area percentage occupied by lymphatic vessels declined significantly (r=-0.581, p<0.001) while an increase in solar elastosis was observed. Percentages of lymphatic vessels were highest at the medial side of the eyelid (p<0.05), and here their relative distribution to the “shallow layer” close to the skin was also highest (p<0.01). Independent of age, the VSS values at 2 weeks and 1 month postoperatively were significantly lower in patients with a higher area percentage of lymphatic vessels (2 weeks: p<0.05; 1 month: p<0.01). ConclusionsIn patients undergoing blepharoplasty, upper eyelid area percentages of lymphatic vessels decreased with advancing age. Higher proportions of lymphatic vessels were associated with improved wound healing outcomes.

The Impact of the Location of Chorda Tymapni Nerve Origin on the Round Window Accessibility During Pediatric Cochlear Implantation: A Radioclinical Assessment.

This study assessed the impact of the location of the chorda tympani nerve (CTN) origin on the round window (RW) accessibility during pediatric cochlear implantation (CI). We also tried to validate the radiologic method to measure the length between the origin of the CTN from the facial nerve to the stylomastoid foramen (CF-SM). It was a prospective observational case-series study. The included CI surgeries were performed at tertiary referral institutions from November 2018 to August 2021. We included 146 pediatric patients who were candidates for CI. We measured the CF-SM length in the parasagittal cut of the preoperative high-resolution computed tomography. We also classified the intraoperative RW according to the accessibility through the ordinary posterior tympanotomy approach into accessible or inaccessible. We correlated the preoperative radiologic CF-SM length with the intraoperative RW accessibility. The radiologic CF-SM length ranged from 2.9 to 7.4 mm with a mean of 4.9 ± 1.03 mm. The RW was accessible in 107 patients and inaccessible in 39 patients. Spearman's correlation coefficient revealed a significant relationship between the location of CTN origin and the RW accessibility as the p value was less than 0.0001. We found a precise method to measure the CF-SM length in the parasagittal cut of the high-resolution computed tomography. We also found a significant impact of the location of the CTN origin on intraoperative RW accessibility. The radiologic CF-SM length of more than 5.4 mm had a powerful prediction capability of the RW inaccessibility.

Validation of the radiological detection of the chorda-facial angle: impact on the round window accessibility during pediatric cochlear implantation

ObjectivesThe facial recess, an essential landmark for the posterior tympanotomy approach, is limited by the facial nerve and the chorda tympani, with a complicated relationship. This study tried to find the most appropriate radiological method to evaluate the chorda-facial angle (CFA). We also checked the effect of this angle on the round window accessibility during cochlear implantation.MethodsIt was a retrospective study that included cochlear implant surgeries of 237 pediatric patients, from September 2016 to April 2021. Two physicians evaluated the CFA in the para-sagittal cut of the preoperative HRCT. The round window accessibility was assessed in the unedited surgery videos.ResultsThe CFA ranged from 21° to 35° with a mean of 27.14 ± 3.5°. It was detected in all cases with a high agreement between the two CT reviewers’ measurements. The CFA differed significantly between the accessible group and the group with difficult accessibility (p value < 0.001). Spearman’s correlation coefficient revealed a strong correlation between the CFA and the intraoperative round accessibility. 25.5° was the best cutoff point; below this angle, difficult accessibility into the RW was expected, with high sensitivity, specificity, and accuracyConclusionsOur study on a relatively large number of cases provided a precise, valid, reliable, and applicable method to evaluate the CFA in the HRCT scan. We found a significant-close relation between the CFA and the round window accessibility; the difficulty increased with a need for posterior tympanotomy modification when the angle decreased.Key Points• Radiological detection of the chorda-facial angle was always problematic, without a previous straightforward method in the literature.• We used the para-sagittal cut of the high-resolution CT scans to evaluate the CFA. This cut was beneficial to seeing the chorda tympani nerve in every examined case. There was a high agreement between the two CT reviewers’ measurements.• Preoperative evaluation of the CFA in the HRCT accurately predicted the round window accessibility. Patients with CFA less than 25.5°were expected to have difficult accessibility into the round window during cochlear implantation.

A novel radiological method to evaluate the posterior tympanotomy depth for cochlear implantation: our experience in 257 patients

PurposeThis study aimed to validate our novel proposed radiological evaluation of the posterior tympanotomy (PT) depth. This dimension represents the bone of the facial recess needed to be drilled to get access into the middle ear during cochlear implantation.MethodsIt was a retrospective observational study that included 257 patients who underwent cochlear implantation from July 2018 to April 2021 in tertiary referral institutions. Two physicians evaluated the preoperative HRCT to measure the PT depth in the oblique para-sagittal cut. On the other hand, two other physicians evaluated the unedited surgical videos to judge the PT depth and classified it into an ordinary PT or deep PT. Then, the preoperative radiological measurements were correlated with the intraoperative findings.ResultsThe radiological PT depth ranged from 2.5 to 5.4 mm with a mean of 3.91 ± 0.886. Sixty-six patients had ordinary PT, and 191 patients had deep PT. Spearman’s correlation coefficient revealed a strong correlation between the preoperative radiological PT depth measurements and the intraoperative PT depth judgments (p value < 0.0001).ConclusionsWe created a novel radiological method to measure the posterior tympanotomy depth. This method was valid, reproducible, and reliable in the preoperative radiological evaluation of the PT depth with high sensitivity (91.71%), specificity (90.62%), and accuracy (91.44%). We also found a significant impact of the PT depth on the PT difficulty during cochlear implantation.

Radiological Analysis of the Facial Recess: Impact on Posterior Tympanotomy Difficulty During Pediatric Cochlear Implantation.

We analyzed several radiological features of the facial recess to correlate them with the intraoperative findings to highlight the most reliable predictors of posterior tympanotomy difficulty. Retrospective observational cohort study. Multicenter study at tertiary referral institutions. We included 184 pediatric patients who underwent cochlear implantation through the posterior tympanotomy approach. The correlation was attempted between 8 radiological features in the preoperative high-resolution computed tomography scan and intraoperative surgical difficulty. Posterior tympanotomy was straightforward in 136 (73.9%) patients. In contrast, it was challenging in 48 (26.1%) patients. The facial recess was aerated in 74.5% of patients. The mean (SD) posterior tympanotomy depth was 3.98 (0.867) mm. The mean (SD) chorda-facial angle was 27.67° (3.406°). The mean (SD) chorda-facial to stylomastoid length was 3.898 (0.6304) mm. The mean (SD) facial nerve second genu angle was 94.54° (6.631)°. Deep-unaerated facial recess wall was associated with the most difficulty. There was a statistically significant difference in the unchallenging and challenging posterior tympanotomy groups regarding the surgical duration (P < .0001). According to this analytic study, the chorda-facial angle, the facial recess aeration, and the chorda-facial to stylomastoid length were respectively the strongest preoperative radiological predictors of the surgical difficulty of posterior tympanotomy during cochlear implantation. Chorda-facial angle <25.5° was associated with difficult posterior tympanotomy. The oblique parasagittal cut was essential for the radiological analysis of the facial recess.

Use of Digitally Annotated and Printed 3D Models for Teaching the Pterygopalatine Fossa

Anatomically deep and geometrically complex regions are difficult for students to visualize in gross dissections, overly simplified in models, and not faithfully depicted in 2D images. One such region is the pterygopalatine fossa which communicates with the infratemporal region, middle cranial fossa, cranial base, nasal and oral cavities, and face via 7 osteological foramina or fissures. Given the geometric complexity of this space, we aimed to create a 3D based educational tool for students to use in their pre‐clinical, dissection‐free head and neck anatomy course.A cranium rendered from CT imaging was imported into Medium, a digital sculpting program, using the Oculus Virtual Reality (VR) system. The right half was removed, and the left half was divided into three sections via two parasagittal slices. The lateral parasagittal cut bisected the foramen rotundum and palatine canals, and the medial parasagittal cut bisected the left half of the nasal cavity. The only alterations to the morphology was an exaggeration of the palatine canal and the anterior and posterior openings of the Vidian canal to allow for the passage of wires during the lab exercise. The three sections of the cranium were then 3D printed. In addition to 3D printing, the model was annotated in Medium by drawing in the course of the maxillary artery and nerve and their branches, and the nerve of the Vidian canal in the pterygopalatine fossa and associated regions. The model showing the neurovasculature related to the pterygopalatine fossa was imported into Sketchfab, a 3D model publishing platform, where labels could be placed to identify structures and provide additional information. The labeled model was embedded into the digital lab manual for students to reference during the lab activity where they were directed to pass a wire through the various foramina and fissures in the region to understand the passage of the neurovasculature in and out of the pterygopalatine fossa.The annotated digital model allowed students to visualize the completed course of these nerves and arteries while the printed model gave appreciation for the location, size, and orientation of the canals and foramina through which the pterygopalatine fossa communicates with other regions. This intervention was applied in the 2019 Living Anatomy: Head and Neck course, where students did not perform dissection but did have access to prosected cadavers and plastinations.Student performance on the 2019 exam was statistically identical to the performance of previous cohorts in a traditional dissection‐based anatomy course (2018: 85.9%; 2019: 88.1%). The 2019 cohort on average scored lower on questions derived from the material from the lab that included this intervention compared to the 2018 cohort (2018: 84.82%; 2019: 80.76%). However, the pterygopalatine fossa question (97.09%) outperformed the nasal cavity (80.58%) and larynx/pharynx (78.5%) questions. Additionally, students ranked digitally annotated 3D models the 3rd highest activity or resource following faculty directed case studies and the prosected cadavers. Student exam results and feedback indicate a utility of providing physical objects with digital 3D reference material during anatomy instruction.

Redirection of Para-sagittal Cuts of Magnetic Resonance Imaging For Temporomandibular Joint

Background: Magnetic resonance imaging (MRI) is the main imaging modality in the diagnosis of temporomandibular disorders. Furthermore, sagittal cuts are the chief plane in diagnosis of these disorders.Aim of the study: This study aimed to investigate the validity of para-sagittal cuts taken parallel to lateral pterygoid muscle in depicting the structures of temporomandibular joint.Subjects and Methods: Twenty symptomatic temporomandibular joint (TMJ) patients performed MRI bilaterally using the traditional para-sagittal cuts and another plane parallel to lateral pterygoid muscle. Four-point scale was used to assess the clarity of articular disc position, disc morphology, cortical bone, and overall quality of the images of both investigated techniques in closed and open positions. Moreover, the final diagnosis of the cases was obtained in each technique.Results: The mean and standard deviation of muscular aligned cuts in clarity of revealing disc position, disc position, cortical bone, and overall image quality in closed position were 2.83 ± 0.39, 2.63± 0.49, 2.53± 0.51, and 2.83± 0.39, respectively, while those for traditional plane were 2.55± 0.50, 2.43± 0.50, 2.80± 0.41, and 2.53± 0.51 with the same order. In open position, the same investigated points got 2.80± 0.41, 2.73± 0.45, 2.73± 0.45, and 2.80± 0.41 in muscular aligned images and 2.78± 0.42, 2.65± 0.48, 2.82± 0.39, and 2.78± 0.42 in the traditional plane. Both techniques provided the same diagnosis in 97.5% of the cases.Conclusion: Parasagittal magnetic resonance images taken parallel to lateral pterygoid muscle deposited higher image quality than the traditional plane in revealing temporomandibular structures.

Abstract PR489

Background & Objectives: The aim is to compare two techniques of ultrasound-guided infraclavicular block (ICB) in parasagittal cut: posterior in the plan versus out- of plan. Materials & Methods: After the approval of the hospital ethics committee, we conducted a prospective study between June 2015 and March 2016. We included 50 patients (ASA I or II) admitted to the operating room for elbow fracture. After their informed consent, they were randomized into two equal groups GP and GA. For all patients, we conducted an ultrasound-guided ICB with a single injection of 40 ml of bupivacaïne 0.25%. For this, we used an ultrasound probe (Sonosite) flathead and high frequency. It was placed in a parasagittal plan at the subcoracoid bursa. A short-axis view of the axillary artery was obtained. For GP, Echoplex needle (100 mm) was inserted above the trapezius muscle. The puncture point was lateralized enough to allow the needle to pass between the clavicle and scapula. IT was directed to the axillary artery and advanced to the lateral cord of the brachial plexus using the technique in-plan. In GA, the needle is inserted laterally to the probe and advanced according to the technique out-of plan until the lateral cord of the brachial plexus. In this group, we measured using the cursor, the distance between the skin and pleura. To avoid the risk of pneumothorax (when we do not visualize the tip of the needle), the maximum length of needle insertion was fixed less than that distance. We compared the two groups, the duration of the procedure, the ICB success rates and patient satisfaction. Statistical analysis was made by SPSS 22. Results:we have not noticed any case of pneumothorax or other major complication. 2 patients of the GP felt paresthesia at the scapula. Conclusion: ICB performed under ultrasound parasagittal approach using the technique anterior out-ofplan has a better feasibility, efficiency and safety than the posterior in-plan.

Immunocytochemical and histochemical analyses of gonadotrophin releasing hormone, tyrosine hydroxylase, and cytochrome oxidase reactivity within the hypothalamus of chicks showing early sexual maturation

In order to determine the changes in gonadotrophin releasing hormone (GnRH) and dopaminergic activity within the brain during the onset of sexual precocity, a Halasz-like knife was developed to produce discrete parasagittal cuts in 2-week-old male broiler chicks. At 5 weeks of age, sexually precocious respondents were selected on the basis of advanced secondary sex characteristics and randomly paired with sham-operated controls. Each pair of birds was perfused with heparinized saline followed by 4% paraformaldehyde. Sections 40 microns thick, obtained throughout the hypothalamus, were immunostained with either anti-GnRH or anti-tyrosine hydroxylase (TH) to ascertain dopaminergic activity. Alternate sections from each pair of brains were also treated with cytochrome oxidase to determine metabolic activity levels or with Nissl stain to localize the knife cuts. Analysis revealed an increase in GnRH immunoreactivity within the bed nucleus of the pallial commissure (nCPa) and paraventricular nucleus (PVN), as well as the median eminence (ME). An increase in TH immunoreactivity was observed in the nucleus intramedialis (nI). Also an increase in metabolic activity was seen in the PVN as revealed by cytochrome oxidase reactivity. It is hypothesized that during the onset of puberty there is an increase in immunoreactive GnRH cell numbers as a result of a decrease in the inhibition of the GnRH system, possibly involving the nI and PVN. The source of the dopamine reported in the ME could be from the nI and other nearby nuclei. Dopamine from the tubero-infundibular area may be one of the putative neurotransmitters responsible for the increased activity of GnRH within the ME of chicks showing precocious puberty.

Paraventricular nucleus efferents mediating photoperiodism in male golden hamsters.

Knife cuts were placed around the paraventricular nucleus of the hypothalamus (PVN) in an effort to identify the pathways mediating gonadal regression in male golden hamsters housed in a short photoperiod. Horizontal cuts dorsal to the PVN only affected photoperiodic responsiveness if they actually damaged the PVN. Coronal cuts caudal to the PVN had no effect on testes regression. Parasagittal cuts adjacent to the medial PVN had little or no effect on gonadal regression induced by short photoperiod. We conclude that efferents of the PVN arising dorsally or medially are not necessary for photoperiodic control of testes function, whereas projections from or through the lateral PVN region descending towards the spinal cord are important.

Knife Cuts Lateral but Not Dorsal to the Hypothalamic Paraventricular Nucleus Abolish Gonadal Responses to Photoperiod in Female Hamsters (Mesocricetus auratus)

Horizontal and parasagittal knife cuts in the hypothalamus of female hamsters (Mesocricetus auratus) were employed to investigate the neural pathways that mediate gonadal responses to photoperiod. Bilateral horizontal knife cuts placed dorsal to the paraventricular nucleus (PVN) did not prevent short-day-induced acyclicity and uterine regression. On the other hand, regardless of photoperiod, animals with bilateral parasagittal knife cuts placed lateral to the PVN continued to exhibit regular 4-day estrous cycles and stimulated uteri. Thus, parasagittal cuts prevented the effects of short days on reproductive physiology. This finding suggests that the lateral efferent projections from the PVN represent an important component of the neural pathway mediating reproductive photoperiodism in female hamsters.

Lateral geniculate lesions alter circadian activity rhythms in the hamster

The suprachiasmatic nucleus (SCN) receives photic input via a direct retinohypothalamic tract (RHT) and an indirect geniculohypothalamic tract (GHT). The neurons giving rise to the GHT are in the intergeniculate leaflet (IGL) of the lateral geniculate nucleus (LGN) and contain neuropeptide-Y (NPY) immunoreactivity. The present study used the neurotoxin, N-methyl aspartate (NMA), to examine the effects of lesions of the LGN on circadian wheelrunning in the hamster. The results are compared to those from control lesioned animals and animals with parasagittal cuts through the hypothalamus. The effectiveness of the lesions was examined with NPY immunohistochemistry of the SCN and IGL. NMA injections destroyed the neurons of the IGL and the adjacent ventral and dorsal divisions of the LGN and greatly reduced NPY immunoreactivity in the SCN. The results of the rhythm studies were: 1) NMA injection into the LGN area produced phase advances if the injection occurred within the 12 hr preceding activity onset and delays or no effect if injected during the 12 hr after activity onset;2) the NMA lesions reduced the rate of reentrainment to 6 hr shifts in the LD 14: 10 photoperiod and advanced the entrained phase angles by about 10 min; 3) the knife cuts advanced the entrained phase angles by about 30 min; 4) neither NMA lesions nor knife cuts altered circadian period in constant dim light. Our results indicate that the GHT is not required for entrainment or normal expression of circadian rhythmicity, but that the GHT does exert an influence on entrainment.

Paraventricular nucleus projections mediating pineal melatonin and gonadal responses to photoperiod in the hamster

Knife cuts were placed around the paraventricular nucleus of the hypothalamus (PVN) in order to identify the pathways mediating photoperiodism and pineal melatonin production in male golden hamsters. Cuts in the coronal plane caudal to the PVN, have no effect on photoperiodic control of the testes unless they actually damage the PVN. Bilateral parasagittal cuts at the medial border of the lateral hypothalamus block short photoperiod-induced gonadal regression. Nighttime levels of pineal melatonin are reduced by these cuts, but unaffected by caudal cuts. Projections from the lateral PVN region descending towards the spinal cord appear to be critical for the control of pineal melatonin production and the control of the testicular function by short photoperiod.

Effect of transection in the brainstem on short-term maintenance of deoxycorticosterone-salt hypertension

Sections were made to determine supraspinal areas that participate in the maintenance of deoxycorticosterone (DOC)-salt hypertension. Blood pressure (BP) falls after cuts which severed: (a) the lateral connections between pons and midbrain, (b) the pathways between caudal hypothalamus and midbrain, and (c) parasagittal between medial and lateral hypothalamus. No changes in BP were found either after coronal cuts that severed a central area located at: (a) the pons-midbrain edge, (b) above the caudal hypothalamus, and (c) the level of the anterior hypothalamic area, or after parasagittal cuts at the level of the capsula interna or after a hypophysial stalk lesion. These results implicate the hypothalamus in the maintenance of DOC-salt hypertension. The hypothalamus-neural lobe system appears not to be involved in the lowering of BP found.

The pathways responsible for the characteristic head posture produced by lesions of the interstitial nucleus of Cajal in the cat.

(1) Experiments were performed in cats to examine effects of lesion of the interstitial nucleus of Cajal (INC) on head posture and the responsible pathway. Unilateral INC lesions resulted in lateral tilt of the head to the opposite side, and bilateral INC lesions resulted in dorsiflexion of the head as reported earlier. Such characteristic head posture was produced by successful kainic acid injections as well as by electrolytic lesions, suggesting that it was not due to damage of nerve fibers passing through the INC, but was produced most probably by damage of nerve cells in the INC. Electromyographic (EMG) recordings in unilateral INC-lesioned cats showed that activity was higher in the ipsilateral than in the contralateral major dorsal neck muscles (biventer, splenius, complexus, and rectus), and also higher in the contralateral than in the ipsilateral obliquus capitis caudalis muscle. The pattern of EMG activity was basically similar either when the cats presented typical head tilt or when their head was fixed to the frame at the stereotaxic plane. Characteristic head posture resulting from INC lesions seems consistent with the head posture produced by activation of these muscles. (2) Interruption of the medial and lateral vestibulospinal tracts did not significantly influence head tilt that had been produced by INC lesions. Characteristic head tilt was produced by INC lesions after cats had received bilateral labyrinthectomies, bilateral lesions of most of the vestibular nuclei, and bilateral aspiration of the cerebellar vermis and most of the lateral vestibular nuclei, indicating that typical head tilt can be produced without the vestibular nuclei and cerebellar vermis. (3) The medial longitudinal fasciculus (MLF) was interrupted at different levels to cut the major descending fibers from the INC. MLF interruption at the caudal midbrain produced typical head tilt, although MLF cut at the caudal pons and medulla was ineffective. Bilateral parasagittal cuts lateral to the MLF in the pons produced severe dorsiflexion of the head, and a subsequent unilateral INC lesion produced no further head tilt. These results suggest that fibers originating in the INC, removal of which is responsible for the typical head tilt, run through the MLF in the midbrain, and leave it in the pontine level.(ABSTRACT TRUNCATED AT 400 WORDS)

Hypothalamic knife cuts attenuate maintenance of deoxycorticosterone acetate-salt induced hypertension

These experiments tested the effects of knife cuts transecting neural pathways associated with the anteroventral third ventricle (AV3V) region on deoxycorticosterone acetate (DOCA)-salt induced hypertension. Coronal knife cuts of the descending medial neural pathway from the AV3V region between the medial preoptic area and anterior hypothalamus did not significantly alter DOCA-salt hypertension. However, parasagittal cuts which separated the AV3V region from the medial forebrain bundle attenuated the hypertension following 5 weeks of DOCa-salt treatment.

Distribution and projections of cholecystokinin-immunoreactive neurons in the hypothalamic paraventricular nucleus of rat.

Analysis of coronal sections from colchicine-treated rat brains reveals that CCK-immunoreactivity (CCK-ir) is present in two distinguishable neuronal systems in the paraventricular nucleus (PVN). More than 60% of these cells were found to be typical parvicellular neurons; the remainder were magnocellular neurons. The magnocellular CCK-ir neurons were concentrated in the medial magnocellular subdivision, while more caudally they formed a ring around a zone of unstained magnocellular neurons. Immunostained parvicellular neurons predominate in medial and periventricular parvicellular subdivisions. The efferent projections of CCK-ir neurons were investigated by looking for retrograde accumulation of CCK-ir in cell bodies after selective knife cuts. A parasagittal cut of the lateral retrochiasmatic area as well as transection of the rostral median eminence resulted in an accumulation of CCK-ir material in a large number of both parvi- and magnocellular neurons. After pituitary stalk lesions, however, increased staining was only seen in magnocellular neurons. It is inferred that the magnocellular (presumed oxytocin-CCK) cells send their axons to the pituitary, whereas axons of CCK-ir parvicellular neurons appear to terminate in the median eminence. After transection of the medial forebrain bundle (MFB), immunostaining increased in a small number of scattered transected fibers proximal to the knife cut and in a few perikarya in the PVN, indicating that very few CCK cells may send descending fibers to the lower brainstem.

Hypothalamic obesity in male rats: Comparison of parasagittal, coronal, and combined knife cuts

The effects of three types of knife cuts on food intake and body weight in males rats are compared: bilateral parasagittal cuts through the medial hypothalamus (medial cuts), bilateral coronal cuts through the posterior hypothalamus (posterior cuts), and a unilateral medial cut combined with a contralateral posterior cut (medial × posterior cuts). The medial and medial × posterior cuts produce similar increases in food intake and body weight in chow-fed rats, whereas the posterior cuts do not alter intake or weight. When fed a high-fat diet, however, the posterior cut rats are mildly hyperphagic and outgain controls, although their weight gain is less than that of the medial and medial × posterior cut rats. All three cut groups display finickiness in additional diet tests. These results are similar to those previously obtained with female rats and indicate that medial parasagittal and posterior coronal hypothalamic cuts sever a common feeding inhibitory system.

Effects of transecting lateral neural connections of the medial preoptic area on maternal behavior in the rat: Nest building, pup retrieval and prolactin secretion

In lactating female rats bilateral parasagittal cuts transecting the dorsolateral neural connections of the medial preoptic area (MPOA) abolished nest building and retrieving components of maternal behavior, while crouching and nursing were unaffected. While few animals with these cuts were suckled when presented with pups the prolactin secretion response was undiminished when suckling did occur. Whereas previous studies have demonstrated that extensive surgical separation of the medial preoptic area-anterior hypothalamic continuum from the lateral preoptic area-lateral hypothalamus disrupts all aspects of maternal behavior, the present study has determined more specifically the zone of fibers essential for the active components of maternal behavior, i.e., nest building and retrieving. These fibers appear to enter/leave MPO dorsolaterally beneath the crossing of the anterior commissure in the region of the bed nucleus of the stria terminalis. These neural connections are not the same as those that regulate prolactin secretion in the lactating rat.

Substance P projections to the entopeduncular nucleus, the medial preoptic area and the lateral septum

In rats, brain substance P-like immunoreactivity (SPLI) was examined following hemisections or parasagittal knife cuts in one hemisphere. The SPLI of the entopeduncular nucleus disappeared following cuts between this nucleus and the caudate, but this SPLI was not affected by cuts posterior to the entopeduncular nucleus or anterior to the caudate. The SPLI of the medial preoptic area and the lateral septum disappeared following parasagittal cuts that reached the interstitial nucleus of the stria terminalis dorsally and the bottom of the brain ventrally. It was suggested that (a) the entopeduncular nucleus receives a SP projection from the caudate, (b) the medial preoptic area receives a SP projection from the interstitial nucleus of the stria terminalis, and (c) the lateral septum receives a SP projection from a region ventral to it.