Convex Border Research Articles

Abstract 162: Indirect Carotid Cavernous Fistula with Oculomotor Nerve Palsy Secondary to Trauma

Introduction Intriguing and uncommon, we present a fascinating case of carotid‐cavernous fistula (CCF) following ocular trauma. Delving into medical nuances and outcomes, this reported case offers valuable insights for clinicians and researchers in the field of ophthalmology and interventional Neurology. Methods An elderly patient presented to the emergency department with diplopia and left eyelid ptosis two weeks after left ocular trauma. The patient had exotropia and hypotropia with restricted movement in all directions but mostly during adduction and infraduction which led to the diagnosis of oculomotor nerve palsy. Computer Tomography (CT) head was obtained which showed mild left proptosis with the prominence of the optic nerve sheath complex, CT angiography revealed asymmetric prominence of the left ophthalmic veins and enlarged left cavernous sinus with outward convex borders. CT face and mandible with IV contrast did not show any bony deformity. The patient underwent cerebral angiography that showed an indirect type 4 cavernous‐carotid fistula. Results A precise incidence of CCF fistula has not been reported so far in the literature but it is estimated to be present in 0.2 % of patients presenting with traumatic brain injury with an increased incidence of 4 % with basilar skull fractures. They can occur spontaneously or following closed skull injury, skull base fractures, or iatrogenically after craniotomies, endoscopic transsphenoidal or sinus surgery, and endovascular procedures. They can be classified based on angiographic arterial architecture (direct or indirect), hemodynamics (high flow or low flow), and etiology (spontaneous or traumatic). Type A are direct fistulas, whereas types B, C, and D are indirect fistulas. Direct CCFs often present with pulsatile exophthalmos, orbital bruit, chemosis, diplopia, ocular redness, orbital pain, swelling, swishing or buzzing sounds, headache, or vision loss. Indirect low‐flow CCFs may be asymptomatic and insidious in onset and mostly present with chemosis and conjunctival injection. Conclusion Indirect carotid‐cavernous fistula rarely occurs secondary to a head trauma without any bony deformity and it's even rare to have an oculomotor nerve palsy on presentation, it should be considered as an etiology when evaluating patients for ocular nerve palsies.

Some morphological structures and histological features of the gills of Binni (Mesopotamichthys sharpeyi)

This study aimed to describe some morphological and histological aspects of the binni fish's gills. Fifteen adult male binni were pulled alive from the Al-Forat River at about (24 - 28) months, immediately after death. The gills of binni were situated on each side of the head beneath a gill cover; the operculum and the gills were made of finger-like long filaments joined to the cartilaginous gill bar. From each filament, numerous fragile lamellae that resemble leaves protrude. These lamellae comprised tiny capillaries covered in plain squamous epithelial cells. The epithelium acts as a barrier between the fish's blood and the surrounding water. The first, second, third, and fourth pairs of gill arches make up the gills supported by the bone skeleton. Each arch carries a row of gill filaments on its convex side and two rows of gill rakers on its concave side. On the rostral concave border, the filaments in the two extremes of the gill were short, but the length of all the filaments was the same. The first-gill arch's lateral rakers were longer than the medial rakers, while the fourth gill arch's medial rakers were longer than the lateral rakers. The rakers, bony comb-like projections, filled the rostral region of the gill arches at the rostral concave interior side. There was interdigitation between the gill rakers of the neighboring gill arches. Each gill arch included the lateral gill rakers pointing dorsolaterally and medial gill rakers pointing dorsomedially. Filaments originate from the gill arches and are maintained by the cartilage on the caudal convex border of the primary lamellae, from which the secondary lamellae emerge. The simple squamous epithelium lined the secondary lamellae. Keywords: Binni, Gill, Morphology, Histology

Morphological and paleohistological description of a new Baurusuchidae specimen from the Adamantina Formation, Upper Cretaceous of Brazil

The baurusuchids were terrestrial notosuchian crocodyliforms from the Upper Cretaceous of South America. The present study analyzes a partial postcranial skeleton, MPMA 62.0002.02, collected in strata from the Adamantina Formation (Campanian-Maastrichtia, Bauru Basin) near the General Salgado municipality, São Paulo state, Brazil. The specimen was identified as a notosuchian, and more precisely to the family Baurusuchidae because of the presence of a dorsal protuberance on the postzygapophysis, robust ribs, a scapula with a dorsal convex border, and a strong middle constriction. The presence of bone tissues with different growth rates signifies that at least some baurusuchids present different allometric rates for the humerus, vertebrae, and osteoderms. The results also show that there may be a shift between fast and slow growth rates throughout life. Our results suggest a a possible correlation between the developmental delay of these animals and the seasonal environmental changes in semiarid conditions. The histological and morphological descriptions proved to be efficient for identifying the Baurusuchidae family, as well as for defining indicators to comprehend the biology of extinct species.

Gross morphological and surface ultrastructural investigation on the gills of the European barracuda Sphyraena sphyraena.

The present work examined 10 gill systems of European barracuda grossly and by scanning electron microscopy (SEM). Grossly, there were four pairs of the gill arches. The convex border of the gill arch carried the gills filaments, but there were abundance of spines near to its concave border and the gill rakers were absent. Laterally near to the convex border of the gill arch, SEM observations revealed that the first gill arch carried small elliptical, oval, cuboidal, and triangular groups of two shapes of spines; spearhead-like spines and canine-like spines, but the other three gill arches carried larger groups of the same shaped spines with the appearance of waterfalls. Medially near to the convex border of the first gill arch, the canine-like spines were observed only in the form of vertical rectangular groups that adhered in some areas. Laterally near to the concave border, the two shapes of spines were present in the form of longitudinal groups separated by spaces at the first gill arch, but these spaces were absent in the other three gill arches. Medially near to the concave border of the first gill arch, the two shapes of spines were presented in oval groups, while the other three gill arches were covered entirely by cuboidal groups of the two shapes of spines. The absence of the gill rakers in conjunction with an abundance of spines helps the European barracuda to control the food particles from escaping to the gill filaments to prevent its suffocation.

Endovascular Treatment Outcome and CT Angiography Findings in Acute Basilar Artery Occlusion with and without Underlying Intracranial Atherosclerotic Stenosis

PurposeTo compare clinical characteristics and treatment outcomes of intra-arterial thrombectomy (IAT) in acute basilar artery occlusion (BAO) with and without underlying intracranial atherosclerotic stenosis (ICAS) and to investigate the usefulness of preprocedural CT angiography findings in the diagnosis of ICAS. Materials and MethodsTwenty patients who received IAT for acute BAO between September 2014 and March 2019 were included. Additional therapies such as angioplasty, stent placement, and tirofiban infusion were provided while treating ICAS. Clinical and angiographic results of treatment were recorded. Preprocedural CT angiography findings in ICAS and non-ICAS groups were compared to assess (i) basilar tip opacification, (ii) partial occlusion, (iii) presence of convex border, (iv) occlusion segment longer than two thirds of the basilar artery or 20 mm, (v) dense basilar artery, and (vi) wall calcification in the occluded segment. ResultsAmong the 20 patients (mean age, 71.3 y; mean stroke score, 24.8), optimal recanalization was achieved in 19 (95%). Three patients had good clinical outcomes. There were 6 patients with underlying ICAS. No difference was observed between ICAS and non-ICAS groups in terms of optimal angiographic recanalization and good outcome. On CT angiography, basilar tip occlusion (100% vs 29%), partial occlusion (100% vs 83%), and long occlusion length (100% vs 14%) significantly differed between the groups (P ≤ .01). ConclusionsIn acute BAO, underlying ICAS does not affect optimal recanalization rate or clinical outcome. Preprocedural CT angiography is a potentially useful tool to detect it.

Morphological studies on the gills of the European hake (Merluccius merluccius, Linnaeus, 1758).

The current work gives concern to study the morphology of the Merluccius merluccius gills by using gross morphology, scanning electron microscopy (SEM), and light microscopy. The findings of the present study revealed that the gill system consisted of four pairs of gill arches which carry the gill filaments on the convex border and gill rakers on the concave border of them. SEM results revealed that the rakers and the spines distribution on the first gill arch differed from that of the other three gill arches on the lateral and medial surfaces. On the surface the gill filaments, there were longitudinal ridges that carried pores of chloride cells and mucous cells. The histological examination revealed that, the gill arch composed of hyaline cartilage that presented in the form of cups. Each cup consisted of central cartilagenous core and peripheral cartilagenous matrix. The gill filaments composed of cartilaginous bar of peripheral cartilaginous matrix and central cartilaginous core extended from the gill arches and covered by an epithelial layers with a few mucous cells permeate it, and chloride cells were straggly in the interlamellar epithelium. Each gill filament carried several leaves like secondary lamellae on both sides of it. The epithelium, which lined the secondary lamellae, composed of epithelial pavement cells, some mucous cells, and pillar cells.

Ultrastructure features of the surface of the gills and the lower pharyngeal jaw of the Tilapia Zilli, redbelly tilapia (Coptodon Zillii, Gervais, 1848).

The present investigation was designed to describe the surface ultrastructure of the gill system of tilapia Zilli. The gill system is formed from four gill arches and each gill arch carries a row of gill filaments on its convex border and two rows of the gill rakers on its concave border. The quadrilateral interbranchial septum has elevated part at the level of the third gill arch. By SEM observations, the gill arch was divided into three regions: rostral, middle and caudal region. The caudal region contained two characteristic structures: oval leaf-like structure and rounded-shaped structure. Each oval leaf-like structure carried two lateral rows of the triangular pointed spines separated by a median groove. All surfaces of gill arches, rakers and filaments were covered with a mosaic of the polygonal pavement cells, in addition to the opening of chloride cells and mucous cells. The gill arch and gill raker had only one appearance of taste buds named type I. Meanwhile, the filaments contained two types of different appearance of the taste buds named: type I and type II. Type I was the main common and similar to that present in gill arch and raker and characterized by its blunt end, while type II had hair-like structures that projected from the volcano-shaped depression. The gill rakers were formed from central axis surrounded by two lateral lobulated regions which carry pointed spines, taste buds and the opening of chloride cells. The surface of triangular lower pharyngeal jaw carries numerous teeth-like papillae which originated from the socket-like depression.

Study of color perceptibility of gonio‐apparent panels with curvature angle

AbstractColor tolerances of curved gonio‐apparent panels have been studied in this work. To achieve that, an experimental set‐up of the illumination and tilt variation of two identical coated panels was designed for simulation of curved panels with both concave and convex borders and with and without effect pigments (perceived as solid and gonio‐apparent colors, respectively). Finally, visual and instrumental measures were collected with both curvatures. The results show that the relationship of the instrumental color difference with the tilt angle can be modeled by a second‐order and the vertex did not depend on illumination, but on coating type. The critical angles (the angle marked when the color discrepancy between two identical samples is merely perceived) assessed by the observers showed that they were not equal according to border, nor according to coating type. The color tolerances at these angles were clearly higher than the conventional chromatic thresholds of industrial color comparisons.

Anatomic and Radiologic Study of Renal Avascular Plane (Brödel's Line) and Its Potential Relevance on Percutaneous and Surgical Approaches to the Kidney.

The aim of the present anatomic and radiologic study was to evaluate the location, extension, and characteristics of the Brödel's plane and eventually define its different patterns. We evaluated 15 human normal kidneys sampled from unembalmed cadavers without clinical history or anatomical evidence of renal diseases. Kidneys with the surrounding perirenal fat tissue were removed en bloc with the abdominal segment of the aorta. The renal artery was injected with acrylic and radiopaque resins. A CT examination of the injected kidneys was performed. After the imaging acquisition, the specimens were treated with sodium hydroxide for removal of the parenchyma to obtain the vascular casts. All the CT images were elaborated using dedicated three-dimensional (3D) software with the aim to improve the possibility to identify the Brödel's plane. The avascular plane was identified directly on the vascular casts and confirmed on the corresponding 3D images. The avascular plane was located in all cases medially to the lateral convex border of the kidneys. The recorded mean distance was 2.04 cm (range 1.8-2.4 cm). Three patterns of distribution of the Brödel's line were identified. In five (33.3%) cases the avascular plane was extended from the apical to the inferior segment of the kidneys (type 1); in six (40%) from the superior to the inferior segment (type 2); and in four (26.7%) from the apical to the middle segment (type 3). Fourth and fifth order vessels crossing the Brödel's line were detected in all the analyzed cases. The renal avascular plane showed a different extension allowing us to cluster three different patterns. Preoperative identification of the Brödel's line patterns could help surgeons to minimize hemorrhagic complications during percutaneous and surgical procedures requiring an incision of the renal parenchyma such as traditional or robot-assisted nephrolithotomy or partial nephrectomy for endophytic renal tumors. Radiologic studies validated that the described patterns in the clinical practice are strongly needed.

Anatomical Study on the Gills with its Respiratory Circulation in Shovelnose Ray Fish (Glaucostegus Typus)

This present study was applied on shovelnose ray fish (Glaucostegus Typus) to investigate the anatomical features of gills and its vascular networks (arterio-arterial pathway) within the gill arch. Twleve fresh specimens were used by applying the intravascular injection technique with red colored latex or Urographin to study the gill vasculature. Fish gills consisted of five pairs of gill arches, opened externally by five branchial slits; each arch supported by a double row of gill filaments along its lateral convex border except the 1st arch had one posterior row. The gill arches were supported by a complete interbranchial septum. The arterioarterial (respiratory) pathway consists of the afferent, the lamellar, the filamental and the efferent segments of the branchial arteries.

The Glen Murray fossil penguin from the North Island of New Zealand extends the geographic range of Kairuku

ABSTRACTThe Glen Murray fossil penguin was one of the first ancient penguins to be reported from the North Island of New Zealand when it was described in 1973. However, its significance for penguin diversity has remained largely unresolved since initial description. Here we show that the Glen Murray penguin exhibits two of three traits that are autapomorphic for Kairuku: the femur is very stout with a midshaft width <15% of the total femoral length and the tibiotarsus has a distinctly convex medial border in distal view. The third trait (absence of the crista medialis hypotarsi) cannot be assessed as the proximal end of the tarsometatarsus is missing. The Glen Murray penguin is most likely a distinct species that should be assigned to the genus Kairuku, although we refer it to Kairuku sp. pending the discovery of more material. Reappraisal of local stratigraphy indicates that the Glen Murray fossil penguin is from the Dunphail Siltstone member of the Glen Massey Formation and can be assigned to the lower Whaingaroan stage (34.6–29.8 Ma).

Detailed morphological description of Habronema clarki Foster & Chitwood, 1937, a nematode parasite of capybaras Hydrochoerus hydrochaeris (Linnaeus, 1766) in Brazil.

The genus Habronema has four valid species, of which only two are properly known. The present study aimed to describe in detail the morphology of Habronema clarki through optical and scanning electron microscopy analyses. Our results showed that the labial morphology of this parasite is closer to H. muscae than to H. microstoma. Even so, the characteristic pseudolabia and the slightly convex border of the dorsal and ventral lips are sufficient to distinguish these nematodes. Additional morphological data are presented, thus contributing to the knowledge on this little known nematode. In addition, this study provides new locality records for this species.

Rheology of granular materials composed of nonconvex particles

By means of contact dynamics simulations, we investigate the shear strength and internal structure of granular materials composed of two-dimensional nonconvex aggregates. We find that the packing fraction first grows as the nonconvexity is increased but declines at higher nonconvexity. This unmonotonic dependence reflects the competing effects of pore size reduction between convex borders of aggregates and gain in porosity at the nonconvex borders that are captured in a simple model fitting nicely the simulation data both in the isotropic and sheared packings. On the other hand, the internal angle of friction increases linearly with nonconvexity and saturates to a value independent of nonconvexity. We show that fabric anisotropy, force anisotropy, and friction mobilization, all enhanced by multiple contacts between aggregates, govern the observed increase of shear strength and its saturation with increasing nonconvexity. The main effect of interlocking is to dislocate frictional dissipation from the locked double and triple contacts between aggregates to the simple contacts between clusters of aggregates. This self-organization of particle motions allows the packing to keep a constant shear strength at high nonconvexity.

Radiographic evaluation of mediastinal lines as a diagnostic approach to occult or subtle mediastinal abnormalities

The mediastinal lines visible at conventional radiography represent the interfaces between the mediastinum and adjacent lung parenchyma. Preservation, obliteration, thickening and distortion of these lines represent the key to detecting and localising mediastinal abnormalities on chest radiographs. The learning objectives of this review are to: illustrate radiographic anatomy of the mediastinum with particular attention to mediastinal lines; describe radiographic signs that allow identification of mediastinal abnormalities that are difficult to detect on conventional chest radiographs; describe findings that help localise abnormalities in the anterior, middle or posterior mediastinum. The anterior junction line obliteration, the hilum overlay sign, the preservation of the posterior mediastinal lines and the silhouette sign with the right cardiac border are radiographic signs that allow identification and localisation of anterior mediastinal lesions. Widening of the right paratracheal stripe, distortion of the azygo-oesophageal recess and the convex border of the aortopulmonary window indicate the presence of a middle mediastinal abnormality. Thickening, distortion or disruption of paraortic and paraspinal lines and posterior junction line obliteration are caused by posterior mediastinal lesions. Knowledge of normal radiographic mediastinal anatomy and mediastinal lines is crucial to identifying subtle mediastinal abnormalities that can be easily missed on conventional radiography. Moreover, this approach allows identification of the involved mediastinal compartment on chest radiographs, thereby directing the most appropriate further diagnostic workup.

Pulmonary infarction associated with bronchogenic carcinoma

Computed tomography findings of pathologically proven pulmonary infarction associated with bronchogenic carcinoma are reported for two patients. In one case, the infarction was demonstrated as a well-defined pleura-based large nodule in the peripheral portion of the same lobe of the tumor. The nodule had a smooth, convex border and a linear strand from the apex of the lesion toward the hilum. The obstruction of the subsegmental pulmonary artery due to tumor invasion was considered the cause of pulmonary infarction. In the second case, the infarction was demonstrated as a rapidly appeared, pleura-based consolidation in the same lobe of the tumor with a blurred border. Obstruction of the pulmonary vein by a tumor might have played an important role in the development of the pulmonary infarction in association with a large pulmonary artery obstruction. We conclude that pulmonary infarction should be considered as a differential diagnosis when peripheral pulmonary nodules or masses are located in the same lobe as the primary cancer.

The effect of aluminium phosphide on the human brain: a histological study

The study was conducted on 317 cases of poisoning in the Varanasi region, India, between January 2002 and August 2003. Aluminium phosphide (Celphos) was used by 239 victims (75.40% of the total) and was used in 69.03% of male and 30.96% of female cases. It was commoner in males from both rural and urban areas and in the 21-30 year age group. Microscopic investigation of the cerebral and cerebellar cortex showed distinct changes due to the effect of celphos. Findings in the cerebral cortex revealed disorganisation of the different layers, round shaped neurons with a convex border, degenerated Nissl granules in the cytoplasm and a deeply stained degenerated eccentric nucleus. Findings in the cerebellar cortex included degenerated neurons, the infiltration of round cells into the molecular layer and the disappearance of the processes of Purkinje cells. Degenerate nuclei were surrounded by scavenger cells in the granular layer. The subcortical zone of the brain revealed a paucity of glial cells, degeneration of nerve fibres and the appearance of necrotic patches.

Rebound thymic enlargement on CT in adults

The objective of this study is to report the development of thymic enlargement in adults, mainly associated with chemotherapy for malignancy. The typical CT features of this phenomenon are described. The clinical data and CT studies of 13 adult patients with newly appearing thymic enlargement on CT were reviewed. These patients were followed-up mainly for malignancy. Further follow-up CTs were studied when available. Medical records were reviewed as to the primary disease, its medical treatment and the time of initial appearance of the enlarged thymus in relation to treatment. The study group included 13 adult patients, 12 with malignant disease and one with a slowly resolving pneumonia. The enlarged thymus appeared as a triangular, arrowhead-shaped structure, with a bilobed configuration and convex borders. Density measurements were consistent with homogeneous soft tissue. Location was in the anterior mediastinum, in the normal site of the thymus. In nine patients, follow-up studies were available. The observation period ranged from 5 months to 8 years from the initial appearance of the enlarged thymus. In five of the nine patients, the thymic enlargement resolved after 1-4.5 years. In four of the nine patients, the thymus remained enlarged during a follow-up ranging from 5 months to 2.5 years. Thymic enlargement, while a rare phenomenon in adults, may occur, mainly after chemotherapy. This phenomenon should be included in the differential diagnosis of a soft tissue mass appearing in the anterior mediastinum on follow-up CT in adult patients particularly following treatment for malignancy.

Pulmonary Infarction

Despite the dual blood supply to the lung, acute pulmonary embolism (PE) can lead to a spectrum of ischemic injury to the lung resulting in infarction and hemorrhage. In this series we systematically describe the spectrum of CT findings and clinical correlates of pulmonary infarction in patients with PE. We retrospectively identified 24 consecutive adults with pulmonary infarction on multidetector CT between July 2002 and March 2004. There were 13 women and 11 men, with a mean age of 59 years. The cases were identified by review of 74 consecutive CTs demonstrating PE. Each CT was evaluated by 2 of 3 reviewers in consensus for presence and characteristics of peripheral parenchymal opacities and extent of PE. Peripheral opacities were evaluated for degree of enhancement, internal air lucencies, and contour. The presence of adjacent vessels and linear strands were noted. At the end of interpreting each case, the reviewers determined whether or not an infarct was present based on the constellation of previously described imaging features. The extent of pulmonary vascular obstruction was graded using the CT clot burden scoring system. Each chart was reviewed for predisposing factors for PE and infarction, presenting clinical symptoms/signs, and co-existing pulmonary or cardiac conditions. Thirty-two percent (24/74) of patients with PE had pulmonary infarction. Thirty-three percent (8/24) of patients had more than 1 infarct. Seventy-three percent (27/37) of infarcts were in the lower lobes. The CT findings of pulmonary infarction included: focal decrease in parenchymal enhancement in 95% (35/37), broad pleural base in 65% (24/37), truncated apex in 57% (21/37), convex border in 46% (17/37), internal air lucencies in 32% (12/37), linear stranding from the apex toward the hilum in 24% (9/37), and a thickened vessel leading to the apex of the infarct in 14% (5/37). There was a trend toward a higher mean clot burden (12.3 vs. 10.5) between the patients with PE with and without infarction. Ninety-six percent (23/24) of patients with pulmonary infarction had predisposing factors for infarction, including PE involving more than 1 lobe (n = 21), malignancy (n = 5), and heart failure (n = 3). Pleuritic chest pain was significantly more frequent in patients with infarction (P = 0.0064). Pulmonary infarction occurred in nearly 1/3 of patients with PE in this series. The infarcts were peripheral parenchymal opacities characterized by a distinctive complex of findings on CT reflecting ischemic injury in the setting of a dual blood supply to the lung. Pleuritic chest pain was significantly associated with infarction.

A NEW STYGOBITIC CRAYFISH FROM MEXICO, PROCAMBARUS CAVERNICOLA (DECAPODA: CAMBARIDAE), WITH A REVIEW OF CAVE-DWELLING CRAYFISHES IN MEXICO

Abstract Procambarus (Austrocambarus) cavernicola, a new species of stygobitic crayfish known only from Gabriel Cave, Oaxaca, Mexico, is described. The new species is characterised by a body that lacks pigmentation, except for small purple spots on the eyes; with small setae on the tip of the eye; elongated chelipeds, with the surface of chela covered with small tufts of short setae; first pleopod of form I male with mesial process elongated and conical, triangular central projection, reduced cephalic process and cephalic shoulder forming convex border; annulus ventralis with preannular plate covered with short setae, postannuluar plate oval-shaped, with blunt tubercles. The new species is morphologically similar to other stygobite members of the subgenus Austrocambarus from the Oaxaca–Veracruz area, whose relationships are discussed. The distributions and levels of adaptation to the subterranean environment of 16 cave-inhabiting taxa of Procambarus in Mexico are reviewed.

A New Stygobitic Crayfish from Mexico, Procambarus Cavernicola (Decapoda: Cambaridae), with a Review of Cave-Dwelling Crayfishes in Mexico

Procambarus (Austrocambarus) cavernicola, a new species of stygobitic crayfish known only from Gabriel Cave, Oaxaca, Mexico, is described. The new species is characterised by a body that lacks pigmentation, except for small purple spots on the eyes; with small setae on the tip of the eye; elongated chelipeds, with the surface of chela covered with small tufts of short setae; first pleopod of form I male with mesial process elongated and conical, triangular central projection, reduced cephalic process and cephalic shoulder forming convex border; annulus ventralis with preannular plate covered with short setae, postannuluar plate oval-shaped, with blunt tubercles. The new species is morphologically similar to other stygobite members of the subgenus Austrocambarus from the Oaxaca–Veracruz area, whose relationships are discussed. The distributions and levels of adaptation to the subterranean environment of 16 cave-inhabiting taxa of Procambarus in Mexico are reviewed.