Light Microscopy Of Histological Sections Research Articles

Протективное влияние различных препаратов на крыс при экспериментальном повреждении гастродуоденальной зоны

The aim of the study was to establish the protective effect of various drugs on rats with experimental damage to the gastroduodenal zone. The object of the study was Wistar rats (n=84) exposed to high-power light effect on days 1, 7 and 14. A comprehensive methodological approach was used, including the study of behavioral reactions, macroscopic assessment of the gastric mucosa and duodenum 12, light microscopy of histological sections of the adrenal glands. It was found that intragastric administration of amino acid-based dietary supplements to rats, at a dose of 0.05 ml per animal, for 14 days, contributes to increased locomotor activity and research function, which can be regarded as a stress-protective effect aimed at suppressing anxiety-depressive changes in the behavior of the studied individuals. The protective properties of the studied dietary supplements, confirmed by an experimental model of damage to the gastroduodenal zone, are distributed according to the corrective effect as follows: BAD-2, BAD-1, BAD-3.

Структурно-функциональная характеристика яичников крупного рогатого скота на разных стадиях полового цикла

The article presents the normative micromorphological characteristics of the ovary of a Blackand- White Holstein cow at different stages of the reproductive cycle (proestrus, estrus, metestrus, anestrus). A complex methodological approach was used, including fine anatomical dissection of freshly extracted eviscerated organs, light microscopy of histological sections of the ovary taken within an hour after slaughter from each individual. The patterns of structural and functional transformations of the elements of the ovary (corpus luteum and follicles), which are characteristic of the normal course of the ovarian cycle of a cow, are presented. The results obtained are the reference for diagnosing the condition of the gonads in cows.

Структурные перестройки кожного покрова у длинноволосых пород кошачьих

The article presents a comparative morphological characteristic of the general coat of long-haired domestic cat breeds (Burmese, British long-haired) and mestizo based on the use of a set of studies, including anatomical preparation, light microscopy of histological sections, micromorphometry and statistical analysis of the obtained digital data. Taking into account the specific, pedigree and topical features of the skin of the studied felines, its general patterns of structure were revealed. It has been established that the skin is divided into 3 layers: epidermis, dermis and hypodermis. In all the animals we compared, the thickness of the skin in the back area exceeds that of the abdomen, which depends on the functional purpose of these regions of the body. Outbred felines reach the maximum value in terms of the total thickness of the skin, epidermis and hypodermis, however, in terms of the thickness of the skin base, longhaired cats are ahead of the mestizo. The bundles of collagen structures of the papillary dermis reach their maximum value in outbred representatives.

DIFFERENTIAL POSSIBILITIES OF THE METHOD OF STAINING HISTOLOGICAL SPECIMENTS BY PERLS FOR ESTABLISHING THE TIME OF FORMATION OF TRAUMATIC AND NONTRAUMATIC GENESIS HEMORRHAGES

Verifi cation of the exact time of formation of hemorrhages in the human brain (HB) of traumatic (HTG) and non-traumatic (HNG) genesis makes it possible to signifi cantly narrow the circle of suspects in the case of a crime against human life.Aim of the work. Developing of forensic criteria for the diagnosis of the age of formation of hemorrhages of traumatic and non-traumatic genesis by light microscopy of histological sections of human brain.Materials and methods. For the study used stained histological specimens of the brain from 80 corpses with a known time of hemorrhage from 2 to 15 days, according to medical documents: in case of death from HNG – 30 histological specimens (1 group), death from HTG – 30 histological samples (group 2), brain preparations in case of death from coronary heart disease were selected for control – 20 samples (group 3).Results. Analyzing the available histopreparations, it was found that the corresponding time dependences of the age of hemorrhage are not linear, but on the contrary have fluctuations in their values – uneven appearance of pigment in HB with a gradual increase in time since the formation of hemorrhages of diff erent genesis.Conclusion. Histological examination of micropreparations of the substance of the brain, stained by the method of Pearls, is not eff ective for determining the age of hemorrhage.

Clinical and morphological substantiation of the comparative effectiveness of the use of antibacterial drugs based on cefapirin in subclinical endometritis in cows

The article presents information on the prevalence of subclinical endometritis in cows, which were carried out on the basis of ZAO breeding farm "Povadino", as well as morphological changes in the mucous membrane of the uterus in this pathology. On the basis of the diagnosis, the animals were treated using various schemes with antibacterial drugs based on cefapirin. The studies were carried out on the basis of the Department of Anatomy and Histology of Animals named after Professor A.F. Klimov FGBOU VO MGAVMiB - MBA named after K.I. Scriabin, as well as at ZAO Povadino breeding plant, cytomorphological studies were carried out on the basis of the Chance Bio laboratory in the period from 2019-2021. According to the principle of analogs, 3 groups of animals with the manifestation of subclinical endometritis (15 animals in each) were formed. The animals of the first (experimental) group were injected with the drug "Mitrek"; the animals of the second (comparative) group - the drug "Metrikur", the animals of the third (control) group were injected with the drug "Tylosinocar" intrauterinely, according to the instructions. A comprehensive methodological approach was used, including clinical examination of animals, fine anatomical preparation, cytomorphological examination of cervical mucus, statistical analysis of the obtained digital data, light microscopy of histological sections stained by the classical technique with hematoxylin and eosin. To determine the extent and etiology of postpartum endometritis in black-and-white Holsteinized cows, obstetric-gynecological clinical examination was carried out, which was carried out according to the generally accepted method. In addition to general clinical methods for diagnosing this pathology, cytomorphological studies of 120 smears of cervical mucus were carried out to objectify the diagnosis. Based on the results of a comprehensive study aimed at identifying subclinical endometritis, it was found that this pathology is observed in 53.55% of the studied animals, macro- and morphological changes in the uterus with subclinical endometritis were revealed. endometrium, due to the influence of pathogenic microflora: Staphilococcus aureus, Escherichia coli, Streptococcus viridans group. And also, based on the results of the studies performed, a comparative assessment of the therapeutic efficacy of drugs based on cefapirin was carried out.

Differential possibilities of classical histological research methods for establishing the genesis of hemorrhages in the human brain substance

Verification of the cause of death (CD) from ischemic cerebral infarction (ICI), hemorrhage of traumatic (GTG) and non-traumatic (GNG) genesis eliminates the violent origin of death. Very often it is difficult to diagnose the genesis of hemorrhage only macroscopically when performing an autopsy, so additional material should be selected for forensic histological examination. Aim of the work. To develop forensic criteria for the differentiation of ICI, GTG and GNG of the brain by light microscopy of histological sections of the human brain (HB). Material and methods. For the study were used native sections and stained histological specimens of HB from 110 corpses in the case of: death from ICI – 30 histological specimens (1 group), which were made of 30 speciments stained by the methods of Nissl and Spiel-Mayer; GNG – 30 histological samples (group 2) – 30 speciments, stained similarly to the previous group; GNG – 30 histological samples (group 3) – 30 speciments stained similarly to the previous group. Brain preparations in case of death from coronary heart disease were selected for control – 20 samples (4 groups) – 20 speciments stained by the methods of Nissl and Spiel-Mayer. Results. Analysis of the obtained data of histological examination of morphological changes of tissue elements of the human brain with different genesis of hemorrhage did not reveal stable relationships between changes in the structure of nervous tissue and the cause of hemorrhage. Conclusion. Given the nonspecificity of degenerative changes in the structural elements of the brain, depending on the genesis of hemorrhage, it can be concluded that morphological methods of histological preparations of the brain do not provide accurate and objective information about the genesis of hemorrhage.

МОРФОЛОГИЧЕСКИЕ ОСОБЕННОСТИ ОБЩЕГО ПОКРОВА КОРОТКОВОЛОСЫХ ПОРОД КОШАЧЬИХ

The aim of the research is characterization of the skin change of the feline family, depending on the breed charac-teristics of the animals. Clarification of relations, breed-specific features of skin of representatives of the felines fam-ily in order to establish the predominant for the development of dermatotropic pathologies is one of the urgent tasks of clinical morphology and dermatology. The general regularities and breed features of the skin cover of short-haired cat were established, taking into account its regional anatomical and physiological features. The inverse relationship between the epidermis thickness and the density of the hair cover of the studied animals was revealed, regardless of the breed identity. A specific glomerate collagen morphology of dermis was found typical for all cats of short-haired breeds. The research was carried out at the Department of Animal Anatomy and Histology named after Professor 
 A. F. Klimov, Moscow State Academy of Veterinary Medicine and Biotechnology after Scriabin, MBA. The object of the study involved 27 individuals of short-haired cats of reproductive age (2-5 years), including Siamese (n=5), Russian blue (n=5), Burmese (n=6), British short-haired (n=7), Bengal (n=4). The research material is the skin. A comprehensive methodological approach was used, including anatomical dissection, light microscopy of histologi-cal sections, micro-morphometry, and statistical analysis of the obtained digital data. The results obtained are the basic for assessing the morphological and functional skin state and identifying morphological changes that occur in the conditions of skin damage repair.

The microarchitecture of the tissues of the shoulder joint in dogs

Up to the present time practically not studied the peculiarities of formation of cartilage in the various compartments of the shoulder joint in dogs, as well as zones of least resistance joints in General. Available studies mainly use visual diagnostic methods, without applying morphological and morphometric. There is no information about age-related cytomorphological transformations occurring in the joint in normal and pathological conditions. In this regard, the aim of our study was to determine the zone of risk of damage to the shoulder joint in dogs. Studies were conducted on dogs and cadaver material, selected from giant, large and mediumsized breeds. Arthroscopic studies of dogs were performed, as well as light microscopy of histological sections of freshly treated samples of joint tissues. As a result of trauma to the joint is transformed physiological synovial folds in sklerozirovanie a pathological form that occurs in German shepherd dogs over 5 years of age in 60% of cases. The process of mineralization of the matrix and the appearance of multiple foci of ossification occurs asynchronously in the cartilage of the head of the humerus and the articular cavity of the scapula. Osteoplastic processes in the area of articulation occur unevenly. Cartilage coating of the articular surface of the shoulder blade is characterized by a more uniform distribution than the articular rotation of the humerus head. The zones of risk of damage to the structures of the shoulder joint in dogs were determined. These include: cranial and medial compartments of the joint, the caudal area of the cartilaginous coating of the humerus, the caudal area of the articular surface of the scapula cavity. The data obtained make up for the information about the diagnosis and risk factors in the development of shoulder joint pathologies in dogs of large and giant breeds. They should be used in clinical diagnosis and surgery of the musculoskeletal system in animals.

АДАПТИВНЫЕ ПРЕОБРАЗОВАНИЯ СВЯЗОЧНОГО АППАРАТА КОЛЕННОГО СУСТАВА У ЛИСИЦ В УСЛОВИЯХ ИЗМЕНЕННОЙ ФУНКЦИОНАЛЬНОЙ НАГРУЗКИ

The aim of the research is identification of complex structural changes of the fox’s knee joint ligaments to ensure its high biomechanical potencies. A promising approach for the study of adaptive and compensatory changes of the joint as a multicomponent biomechanical system is to evaluate the structural transformations of its ligaments under conditions of a new functional load. The research was carried out on the basis of the Department of Animal Anato-my and Histology named after Professor A. F. Klimov «Moscow state Academy of Veterinary Medicine and Biotech-nology – MBA named after K. I. Scryabin» and on the basis of JSC «Breeding animal farm «Saltykovsky». The arti-cle presents information about morphological transformations of the lateral and median ligaments of the knee joint that determine its reliable stability. Numerous structural changes of the fox ligaments during cage housing is re-flected, which decrease in the thickness of bundles of collagen fibers and their compositional density compared to the standard structure (in wild individuals). Morphological transformations that can significantly reduce the strength and elasticity resistance of the ligaments and the biomechanical potential of the joint are shown. 23 fox individuals, including 15 individuals of the cage housing and 8 representatives of the natural habitat were studied. The re-search used a comprehensive methodological approach, including anatomical preparation, light microscopy of histological sections, scanning electron microscopy, micromorphometry and statistical analysis of the obtained digi-tal data. According to the results of the study, it was found that fox individuals from natural biocenosis, have colla-gen structures of the lateral ligaments different in waving and packing density from ones of cage housing, which can contribute to ensuring their biomechanical domination.

Морфологические особенности общего покрова у длинноволосых пород кошачьих

The article presents a comparative characteristic of the skin in long-haired cat breeds based on the use of morphological research methods, including anatomical preparation, light microscopy of histological sections, micromorphometry and statistical analysis of the obtained digital data. The general patterns and breed characteristics of the skin in long-haired cats have been established, taking into account its anatomical and topographic features. An inverse relationship was found between the thickness of the epidermis and the thickness of the hair cover in the studied animals, regardless of breed. The specific glomerular design of collagen structures of the dermis was established in all long-haired cat breeds. It has been shown that the depth of the hair follicles and the density of the hair are determined by the topical features of the skin.

The internal anatomy of Sandersiella chilenica Stuardo & Vega, 2011 (Crustacea: Cephalocarida)

AbstractThe gross internal anatomy of the cephalocarid crustacean Sandersiella chilenicaStuardo & Vega, 2011 is described based on light microscopy of histological sections of three specimens of the type series, all collected in coastal soft bottoms off central Chile. Observations mainly concern the nervous, digestive, and reproductive systems, heart, haemocoel, and skeleto-musculature. The main organ systems and musculature are similar to those previously described for Hutchinsoniella macracanthaSanders, 1955, Lightiella magdaleninaCarcupino, Floris, Addis, Castelli & Curini-Galletti, 2006, and Sandersiella sp.

Oral sucker in Digenea: structure and muscular arrangement

Digeneans use oral and ventral suckers for attachment, locomotion, and feeding. The structure of these organs is rarely described in detail. I used fluorescent actin staining and confocal laser scanning microscopy to describe musculature arrangement in the oral sucker of eight digenean species (all Plagiorchiida). Scanning electron microscopy and light microscopy of histological sections were used for a general morphological description of the sucker structure. The musculature of the oral sucker is independent from the body wall and the internal muscles. The arrangement of the muscles within the oral sucker is complex; it includes up to 14 groups. Layers of transverse and meridional muscle fibers line the outer surface beneath tunica propria. Transverse muscle bands, meridional fibers, anterolateral groups, and circular or semicircular fibers of the sphincter are present at the rim of the oral sucker. Circular and longitudinal muscle fibers are found beneath the tegument of the buccal cavity. The bulk of the sucker consists of radial muscle bundles, but it also contains chordal muscle bundles, diagonal fibers, and wide lateral muscle bands. Based on the results, I propose that three features determine the complexity of musculature arrangement in the oral sucker: (1) bilateral symmetry of the sucker, (2) incongruity of the main body axis and the own axis of the sucker, and (3) regionalization of the sucker surface. The origin and functioning of the oral sucker are discussed.

Unusually abundant and large ciliate xenomas in oysters, Crassostrea virginica, from Great Bay, New Hampshire, USA

During routine histological examination of oysters (Crassostrea virginica) from Great Bay, New Hampshire, USA, a high prevalence and intensity of ciliate xenomas has been noted since sampling began in 1997. Xenomas are hypertrophic lesions on the gills of bivalve molluscs caused by intracellular ciliates, likely Sphenophrya sp. Although not known to cause mortality in oysters, xenomas have not previously been reported at this high abundance. The objectives of this study were to characterize the xenomas, describe the ciliates, and gather baseline epizootiological data with correlations to environmental and biological parameters.Upon gross examination, xenomas appeared as white nodules, up to 3mm in diameter, located in the gill tissue and occasionally fusing into large masses along the gill filaments. Light microscopy of histological sections revealed xenomas located in the gill water tubes, which they often completely blocked. Higher magnification revealed dual nuclei, eight kineties, and conjugation of the ciliates. Transmission electron microscopy revealed dual nuclei that varied in density, a maximum of twenty cilia in each kinety radiating from the oral apparatus to the posterior, and a 9+2 axoneme structure within the cilia. These traits place the ciliates into the Order Rhynchodida, but insufficient molecular data exist to confirm classification of this ciliate to the Genus Sphenophrya. Since 1997, xenoma prevalence has fluctuated with peaks in 2000, 2004, and 2011. Infected oysters generally contained <30 xenomas, but 2.1% contained >100, sharply contrasting the rare prevalence and low intensity reported elsewhere. Prevalence increased with oyster size, leveling off near 50% in oysters >60mm. Infection intensity peaked in 70–90mm oysters and declined in larger oysters. Individual oyster condition was not associated with xenoma intensity, but sites with oysters in higher condition generally had a greater prevalence and intensity of xenoma infections. Seasonal data indicated an infection cycle increasing from summer to fall, peaking at 55–65% in November and dropping to <10% by spring. The oyster population in Great Bay, NH warrants further examination to understand the mechanisms and conditions controlling xenoma formation.

ADaphniaParasite (Caullerya mesnili) Constitutes a New Member of the Ichthyosporea, a Group of Protists near the Animal–Fungi Divergence

Caullerya mesnili is a protozoan endoparasite in the gut epithelium of Daphnia, which causes regular epidemics in lakes throughout Europe. Its classification has remained unchanged for over a century, leaving it placed with the Haplosporidia, despite speculation that this position is incorrect. The difficulty in classifying C. mesnili stems from its few known morphological and ecological characteristics, as well as a lack of genetic markers. Here we sequenced the nuclear small subunit (SSU) and internal transcribed spacer rDNA regions of C. mesnili samples from 10 locations. Based on sequence similarities, we suggest the re-classification of C. mesnili to the Ichthyosporea, a class of protists near the animal-fungi divergence. We report average intragenomic variation of 0.75% and 2.27% in the SSU and internal transcribed spacer regions, respectively. From electron micrographs and light microscopy of histological sections we determined that C. mesnili spores grow within the intestinal epithelium where they establish themselves intercellularly. In addition, we confirmed previous accounts regarding the high virulence of this parasite. Caullerya mesnili reduces host lifespan, the number of clutches, and the total number of offspring. This high selection pressure placed on hosts supports the importance of C. mesnili as a model parasite for the study of host-parasite biology in permanent lakes.

Application of optical non‐invasive methods in skin physiology: a comparison of laser scanning microscopy and optical coherent tomography with histological analysis

Optical, non-invasive methods, such as fluorescence laser scanning microscopy (LSM) and optical coherent tomography (OCT), have become efficient tools for the characterization of the skin structure in vivo, as well as real-time investigation of distribution and penetration of topically applied substances. In the present paper, the results obtained with both non-invasive methods - OCT and LSM - were compared to conventional light microscopy of histological sections. Skin structure and the distribution of topically applied particulate and non-particulate substances on the skin surface and in the epidermis were analyzed. None of the methods used are suitable for the realization of all diagnostic tasks, however, each method has advantages for particular applications. Fluorescence LSM is well suited for the investigation of the upper 150 microm of the skin as well as for the investigation of the kinetics of substances applied onto or into the epidermis. OCT can be applied for the investigation of vertical cross-sections of the skin up to a depth of 2 mm, albeit at lower resolution than achieved by LSM or conventional light microscopy. Conventional light microscopy of histological sections of biopsy specimens produces familiar high-resolution images of deeper tissue layers. However, the analysis of the kinetic processes is limited in this case. LSM- and OCT-measurements are efficient non-invasive tools for the characterization of morphological structures of the skin. On the one hand, the optical methods have a clear advantage in the case of kinetic measurements. On the other hand, histological investigations are characterized by a high information density and a high resolution, also in deep tissue layers. The selection of the best method for the analysis of the skin morphology depends on the target and the task of the investigation.

Structure of white rhinoceros (Ceratotherium simum) horn investigated by X-ray computed tomography and histology with implications for growth and external form

The nasal and frontal horns of two individuals of Ceratotherium simum were examined by x-ray computed tomography (CT scanning), gross observation of sectioned horn, and light microscopy of histological sections of the horn tissue. CT scans of both sets of horns reveal a periodic banding pattern that is evident upon gross observation of sections as darker bands of tissue. The overlap of these bands in both histological and CT slices suggests the presence of both a photoabsorbent component (melanin) and a radiodense component (calcium phosphate salts, most likely hydroxyapatite or octocalcium phosphate). The distribution of these two components in the horns is hypothesized to contribute to the differential wear patterns that produce the characteristic sweeping conical shape of rhinoceros horn from what otherwise (in the absence of wear and UV exposure) would be cylindrical blocks of constantly growing cornified papillary epidermis. Although extant rhinocerotids are unique in possessing a massive entirely keratinous horn that approximates the functions of keratin-and-bone horns such as those of bovid artiodactyls, the tissue structures that make up the horn are strikingly convergent with other examples of papillary cornified epidermis found in horses, artiodactyls, cetaceans, and birds.

Membrane thickness and PROM—high-frequency ultrasound measurements

Premature rupture of the membranes (PROM) is still an unsolved problem in obstetrics. Neither prevention nor diagnosis nor therapy is readily available. The amniotic sac is stabilized mechanically by a dense network of collagenous fibres; in the event of PROM, the collagenous mesh is dissolved and the thickness of the amniotic sac is reduced. In a prospective study involving 32 patients, we measured the thickness of the membranes in vitro by high-frequency ultrasound and by light microscopy of histological sections, between gestational weeks 28 and 32. We compared 18 patients with premature rupture of the amnio-chorionic membrane with 14 patients following induction of labour, with intact membranes at the same gestational age in vitro. We were able to show that the membrane in the PROM group (0.54 +/- 0.9 mm) was markedly thinner with fewer collagenous fibres than in the control group (0.74 +/- 1.01 mm). The application of high-frequency ultrasound in vivo in PROM may become helpful for the prediction of PROM; further studies are therefore desirable.

Tumor growth in a defined microcirculation.

The fate of human tumor cells deposited in rat uteri was investigated by light microscopy of histological sections, immunohistochemistry, and scanning electron microscopy of microvascular corrosion casts. The human colonic tumor cell line LS 174 T was used as graft since it can be detected by CEA immunohistochemistry, and spayed nude rats (PVG rnu/rnu) were used as hosts, subjected to different hormonal regimens (no exogenous hormones, medroxyprogesterone acetate, 17-beta-estradiol, or the last two regimens in combination). Intrauterine deposition of a suspension of 2 x 10(6) tumor cells resulted in tumor take in 72% (21/29) of the nude rats. Endometrial growth was verified in only three animals (14%, 3/21). Extraendometrial growth, however, was found in all animals with tumor take. These observations suggest that the endometrium is comparatively resistant to growth of xenografted human colonic tumor cells. The tumor microcirculation consisted of new vessels, giving morphological evidence that tumor growth is dependent on angiogenesis and not on invasion of preexisting vessels.

Ethylene oxide gas sterilization does not reduce the osteoinductive potential of demineralized bone in rats.

It has been shown that different sterilization procedures of demineralized bone may influence its osteoinductive properties. The aim of this study was to evaluate the effect of ethylene oxide sterilization for 1, 3, and 6 hours on the osteoinductive potential of allogeneic demineralized bone implanted heterotopically in rats. Sixty male Wistar rats were randomly assigned to one of four groups, A through D, and four demineralized bone chips (2.8 mg) were implanted in a pouch created between the right oblique abdominal muscles in each animal. In Group A, the demineralized bone was implanted without prior sterilization of the material, whereas the demineralized bone implanted in Groups B, C, and D had been sterilized in ethylene oxide gas for 1, 3, or 6 hours, respectively, and aerated for 48 hours. At 4 weeks postoperatively, bone formation was evaluated quantitatively by strontium 85 uptake and qualitatively by light microscopy of histological sections. One-way analyses of variance at the 0.05 level revealed no significant difference in strontium 85 uptake of the different groups, and no qualitative differences in osteoinduction could be detected by light microscopy. Ossicles consisting of bone and bone marrow were seen in the recovered implants of all groups.

Proteins released by cultured Day 15-16 conceptuses prolong luteal maintenance when introduced into the uterine lumen of cyclic ewes.

Experiments were performed to determine whether proteins, produced and released into the incubation medium by Day 15-16 sheep conceptuses cultured for 24-48 h, could prolong the functional lifespan of the corpus luteum (CL) when infused into the uterine lumen of cyclic ewes. Beginning on Day 12 (oestrus = Day 0) either a concentrated (2 ml) solution of total conceptus culture medium protein (2.2 mg) or diluted sheep serum (2.2 mg protein) was introduced daily via an indwelling catheter into the uterine lumen of 3 ewes for 7 days (Days 12-18). Peripheral blood samples were collected daily for 14 days (Days 12-25). On Day 25 all ewes were laparotomized and ovaries observed to determine whether CL previously marked with India ink were maintained. All controls had ovulated and formed new CL. By contrast none of the conceptus protein-treated ewes had ovulated, and their peripheral progesterone levels remained elevated. One ewe maintained a functional CL until Day 52 when she was hysterectomized. Light microscopy of histological sections prepared from the endometrium revealed glandular development comparable to that in the endometrium of cyclic animals during late dioestrus. The cells of the CL were similar to those from cyclic animals during mid- to late dioestrus. Ovine trophoblast protein ( oTP -1), a major protein secreted by the sheep conceptus between Days 13 and 21 of pregnancy, was purified from conceptus incubation medium and injected (0.2 mg protein/day) into the uterine lumen of 3 animals. Plasma progesterone concentrations indicated that oTP -1-treated animals maintained luteal function 4 days longer than did control animals.(ABSTRACT TRUNCATED AT 250 WORDS)