Histology and functional morphology of the female reproductive tract of the tortoise Gopherus polyphemus

The oviducts of 25 tortoises (Gopherus polyphemus) were examined by using histology and scanning electron microscopy to determine oviductal functional morphology. Oviductal formation of albumen and eggshell was of particular interest. The oviduct is composed of 5 morphologically distinct regions; infundibulum, uterine tube, isthmus, uterus, and vagina. The epithelium consists of ciliated cells and microvillous secretory cells throughout the oviduct, whereas bleb secretory cells are unique to the infundibulum. The epithelium and endometrial glands of the uterine tube histologically resemble those of the avian magnum which produce egg albumen and may be functionally homologous. The isthmus is a short, nonglandular region of the oviduct and appears to contribute little to either albumen or eggshell formation. The uterus retains the eggs until oviposition and may form both the fibrous and calcareous eggshell. The endometrial glands are histologically similar to the endometrial glands of the isthmus of birds, which are known to secrete the fibers of the eggshell. These glands hypertrophy during vitellogenesis but become depleted during gravidity. The uterine epithelium may supply "plumping water" to the egg albumen as well as transport calcium ions for eggshell formation. The vagina is extremely muscular and serves as a sphincter to retain the eggs until oviposition. Sperm are found within the oviductal lumen and endometrial glands from the posterior tube to the anterior uterus throughout the reproductive cycle. This indicates sperm storage within the female tract, although the viability and reproductive significance of these sperm are unknown.     

Structure of the female genital glands of the oviduct in the opisthobranch mollusc, Runcina

Runcina is a small hermaphroditic opisthobranch which possesses a monaulic reproductive system. In previous studies the male copulatory apparatus, the structure of the spermatophore and also the process of oogenesis have been described. The present paper gives an account of the ultrastructure of the female genital glands of the oviduct. In Runcina the oviduct comprises three primary regions, the albumen gland, the egg capsule gland and the mucous gland. Eggs enter the fertilization chamber and as they pass the opening of the albumen gland they become surrounded by albumen or perivitelline fluid. The eggs appear to become encapsulated as they traverse the egg-capsule gland and are eventually stuck together by mucus to form an egg mass. The epithelial lining of the three glands consists of alternating ciliated and secretory cells. The characteristics in secretory products of the glandular cells are described, and are discussed with reference to the way they contribute to egg vestment.     

Observations on the ultrastructure of the oviduct of the Costa Rican green turtle (Chelonia mydas L.)

Unpublished investigations have shown that at the light microscope level the oviduct of the green turtle (Chelonia mydas L.) has two glandular subdivisions each of which appears to be structurally homogeneous. Histochemical studies suggest that the function of the more cranial of these is albumen secretion and that this is its sole function; in its ultrastructural features also it resembles the albumen secreting subdivision (magnum) of the avian oviduct except that it lacks the terminal mucous region to which the formation of the thick layer of egg albumen has been attributed. Layering of albumen (thick and thin layers) is not a characteristic of turtle eggs.The more caudal glandular segment presents ultrastructural features which tend to support the hypothesis that this is the site of shell-membrane formation but the presence of eggs undergoing calcareous shell formation in this subdivision shows that despite its structural homogeneity it is functionally dualistic, secreting both shell membranes and calcareous shell. In the available material ultrastructural features indicative of the latter function could not be demonstrated and further work is required in relation to calcium localization and acid phosphatase which may play a significant rôle in calcium transportation. The glands of the avian uterus in which calcareous shell deposition occurs are believed to be concerned with the addition to the albumen of plumping water. There is evidence that this addition is not a feature of turtle eggs and this may explain the absence of comparable glands in turtle.     

Immunolocalization of laminin during estrogen-induced differentiation of quail oviduct epithelial cells

During estrogen-induced development of the quail oviduct, tubular glands are formed by evagination of epithelial cells into the stroma. The distribution of laminin was studied during the early stages by means of immunofluorescence and immunoperoxidase techniques. Ultrastructural changes in the basal lamina were studied by electron microscopy. Basement membranes at all stages of development were delineated with 3 polyclonal antilaminin antisera. However, in ovariectomized birds, laminin could not be detected by one of the polyclonal antilaminin antisera. Subsequently, this antibody detected laminin as epithelial cell evaginations were induced by estradiol benzoate. The heavy and light chains of Engelbreth Holm sarcoma (EHS) laminin were revealed in immunoblotting by all antibodies. By electron microscopy after the immunoperoxidase technique with antilaminin antisera laminin appears to be accumulated mainly in the lamina densa. Furthermore, the thickness of the basal lamina increases during oviduct development. These data indicate that basal lamina organization is modified during oviduct cell differentiation and that immunoreactivity of epithelial basement membrane laminin changes during development.     

Cloning and characterization of a candidate nutritive glycoprotein from the albumen gland of the freshwater snail, Helisoma duryi (Mollusca: Pulmonata)

Abstract. The albumen gland is a female accessory sex gland that synthesizes and secretes perivitelline fluid around pulmonate eggs. The perivitelline fluid is composed of mainly galactogen and proteins, and is thought to provide nourishment to the embryos during development. We have previously identified the major secretory protein of the albumen gland of the freshwater snail Helisoma duryi as a native glycoprotein of ∼288 kDa, consisting of four 66-kDa subunits. In this study, the major albumen gland protein in H. duryi was purified, cloned, and the full-length cDNA sequence determined. Nucleotide sequence analysis revealed that the albumen gland protein (HdAGP) shared 83% identity with a partial cDNA sequence from a developmentally regulated albumen gland protein in Biomphalaria glabrata . The HdAGP mRNA was detected by RT-PCR in the albumen gland, ovotestis, mantle and digestive gland. SDS-PAGE analysis of the albumen gland protein in egg masses at different stages of development showed that the amount of HdAGP steadily decreased during embryogenesis, suggesting its possible catabolism by the developing embryos. Protein domain searches suggested that the HdAGP shared limited sequence identity, and adopted a similar three-dimensional conformation to the bactericidal, permeability increasing, protein family, raising the possibility of a potential bactericidal function for this important reproductive/developmental protein.     

Effect of infection with Trichobilharzia ocellata and Schistosoma mansoni on the ultrastructure of the albumen gland of their respective hosts, Lymnaea stagnalis and Biomphalaria glabrata

The albumen gland, a female accessory sex gland of pulmonate snails, produces the perivitelline fluid. The ultrastructure of the albumen glands of control and infected specimens of Lymnaea stagnalis and Biomphalaria glabrata was studied. The albumen gland of L. stagnalis contains two types of secretory cells--light (active) and dark (inactive)--and two types of supporting cells--centroacinar and myoepithelial. The secretory cells apparently represent two activity stages of one type of cell. The gland B. glabrata possesses only one secretory cell type, which alternates with one type of supporting cell. The albumen glands of L. stagnalis and B. glabrata infected at a juvenile stage were studied 4 and 14 weeks (L. stagnalis) and 4 and 9 weeks (B. glabrata) after exposure. After four weeks' infection, B. glabrata produced some egg masses, but in subsequent stages egg mass production completely coased. Infected L. stagnalis never produced eggs. B. glabrata was apparently infected at a "physiologically" more mature stage than L. stagnalis. The morphology of the albumen glands four weeks after exposure (the daughter sporocyst stage) is in agreement with this hypothesis. At this interval the secretory cells of L. stagnalis appeared to be much more severely affected (inactive Golgi bodies and rough endoplasmic reticulum, crinophagy of the secretory granules) than the cells of B. glabrata. In the later stages studied (shedding of the cercariae), the glands of both species appeared to be completely inactive (reduced height of the epithelium, inactive organelles, crinophagy, absence of secretory granules). At this stage of infection, daughter sporocysts containing cercaria embryos were seen in the connective tissue of the albumen gland of B. glabrata, but not of L. stagnalis. The results thus indicate that the development and synthetic activity of the albumen gland are seriously affected by infection. These processes are known to be under the endocrine control of the female gonadotrophic hormones. Since it has been established that these hormones are normally present in the haemolymph of infected snails, the findings can be explained by assuming that the parasite interferes in some way or other with the snail's endocrine system.     

Ultrastructure of Pharyngostomoides procyonis Harkema 1942 (Diplostomatidae). II. The female reproductive system

Several components of the female reproductive system of Pharyngostomoides procyonis, including the vitellaria and vitelline duct, ovary and oviduct, Laurer's canal, and Mehlis' gland and associated ducts, were observed with the electron microscope. Vitelline follicles contain cells in various stages of development. Mature vitelline cells contain membrane-delimited clusters of vitelline globules near the plasma membrane. Cilia are present in the vitelline duct. The ovary contains germ cells in various stages of maturation. Oogonia are found in the peripheral region. Mature oocytes contain numerous dense bodies near the plasmalemma. Also included in the cytoplasm of mature oocytes are "nucleolus-like bodies," myelin-like bodies, and mitochondria containing dense granules and few cristae. The epithelium of the oviduct is ciliated. Sperm are present in the oviduct and in Laurer's canal. Two types of secretory cells found in Mehlis' gland are described.     

Recherches sur les ecdysteroïdes présents dans les cocons de la sangsue Hirudo medicinalis au cours de l'embryogenèse / Investigations on the ecdysteroids in the cocoons of the leech Hirudo medicinalis during embryogenesis

Summary

In earlier studies, we demonstrated that leeches contain ecdysone and 20-hy- droxyecdysone. The titre of these molecules was found to fluctuate during the moult/intermoult cycle which is suggestive of a role of ecdysteroids in the control of cuticulogenesis in Hirudinea similar to that observed in Arthropods.

We have now extended our investigations to embryonic development in the leech Hirudo medicinalis. During this period of development, which lasts some 30 days, 5–25 embryos grow inside a large cocoon at the expense of a proteolipidic gel (‘albumen’) synthesized by clitellian glandular cells of the parent leech. We have found that the albumen already contains ecdysteroids before the onset of embryogenesis (‘parental ecdysteroids’). At this time, and during the early stages of embryogenesis, several as yet unidentified low polar ecdysteroids predominate in the albumen; the titre of these molecules shows a dramatic decrease in the albumen at mid-embryogenesis which is concomitant with a marked rise in the concentration of free ecdysone and 20-hydroxyecdysone. In the embryos, this stage coincides with a remarkable transformation of the first structures (‘the cryptolarval metamorphosis’). At all stages investigated the albumen contains significant amounts of Helix hydrolysable conjugates. At least in early stages, the hydrolysis of these conjugates yields free ecdysone and a low polarity ecdysteroid.

We suggest that in Hirudo the ecdysteroids synthesized before egg-laying by the adult leech play a role in the control of embryonic development and possibly also in the as yet not understood cycle(s) of embryonic cuticulogenesis.     

Seasonal changes in the oviduct of the pied myna (Aves: Sturnidae)

Study of the oviduct of the pied myna (Sturnus contra contra) throughout the year reveals that oviductal weight, length, surface epithelial height and glycogen content are low during August to January (nonbreeding phase), partially increase during February to April (pre-breeding phase), maximally increase in May (breeding phase) and decrease in June and July (post-breeding phase). In the nesting cycle, there is greatest growth in all the regions of the oviduct from early nest-building to the egg-laying period and this is followed by rapid involution during incubation and nestling periods. Some notable features in the oviduct of the pied myna are described: 1) All five regions of the oviduct (infundibulum, magnum, isthmus, uterus, and vagina) are clearly distinguishable when studied from serial sections of the oviduct even during the nonbreeding phase of the annual ovarian cycle. 2) There is a strong correlation between initiation of tubular gland formation and the onset of nestbuilding activity. 3) The distal part of the magnum is differentiated into a 'mucous region' having well developed basal nonciliated cells. 4) A sixth zone can be identified between the magnum and isthmus. Sperm hostlike glands exist at the cranial end of the zone. 5) Several circular epithelial invaginations are evident in the intermucosal folds and their size decreases in centripetal order in the vagina. 6) The pattern and degree of regression are different in various regions of the oviduct. A close synchrony between ovarian and oviducal cycles is indicated in the pied myna (Sturnus contra contra).     

DEVELOPMENT OF THE MAGNUM REGION OF THE OVIDUCT IN RELATION TO THE REPRODUCTIVE CYCLE OF THE BARBARY DOVE STREPTOPELIA ROSEOGRISEA VAR.

The magnum region of oviducts of female Barbary Doves was examined at different phases of development before egg laying, and during incubation and brooding of the young. The tubular glands in the mucosal folds of the magnum region increased in size with increase in precursor albumen granule content during the pre-egg-laying phase, and decreased during incubation and brooding. Enlargement of tubular glands was correlated with an increase in plasma progesterone level. The temporal relationships between ovarian development, ovarian hormones, oviduct development and nesting behaviour are discussed.     

Oviductal cell proteome alterations during the reproductive cycle in pigs

The mammalian oviduct plays a crucial role in events leading to the establishment of pregnancy. During the reproductive cycle, the reproductive system undergoes various changes, including alterations in the number of different cell types in the oviductal epithelium and changes in the height of oviductal cells. Maintaining the unique oviductal environment required for the fertilization and early embryonic development comes with an energy cost to the organism. Therefore, it is hypothesized that structural and functional changes to the oviduct during the reproductive cycle represent vital preparations for the development of suitable environments for conception and embryo support. Here, we aimed to identify the changes in protein expression profile that occur during the follicular and luteal stages of the reproductive cycle in oviductal epithelial cells. The porcine oviductal epithelial cell proteomes from the follicular and luteal stages of the reproductive cycle were contrasted after separation by 2-D gel electrophoresis. Several oviductal epithelial cell proteins were up- or down-regulated during the reproductive cycle. We checked the quantitative changes of two of these molecules during different stages of the reproductive cycle using Western blot analysis. Finally, a number of these proteins were identified using tandem mass spectrometry. The results demonstrated distinctive differences in the proteomic profiles of the oviduct between follicular and luteal phases of the reproductive cycle.     

The reptilian oviduct: a review of structure and function and directions for future research

The reptilian oviduct is a complex organ with a variety of functions (albumen production, eggshell production, placentation, oviposition or parturition, and sperm storage), depending on the parity mode of the species in question. These functions are under complex physiological control, the details of which are far from understood. The aims of this review are to summarise the information available concerning the structure and functions of the reptilian oviduct and to highlight areas in particular need of further research.     

Prolonged in vivo functional assessment of the mouse oviduct using optical coherence tomography through a dorsal imaging window

The oviduct (or fallopian tube) serves as an environment for gamete transport, fertilization and preimplantation embryo development in mammals. Although there has been increasing evidence linking infertility with disrupted oviduct function, the specific roles that the oviduct plays in both normal and impaired reproductive processes remain unclear. The mouse is an important mammalian model to study human reproduction. However, most of the current analyses of the mouse oviduct rely on static histology or 2D visualization, and are unable to provide dynamic and volumetric characterization of this organ. The lack of imaging access prevents longitudinal live analysis of the oviduct and its associated reproductive events, limiting the understanding of mechanistic aspects of fertilization and preimplantation pregnancy. To address this limitation, we report a 3D imaging approach that enables prolonged functional assessment of the mouse oviduct in vivo. By combining optical coherence tomography with a dorsal imaging window, this method allows for extended volumetric visualization of the oviduct dynamics, which was previously not achievable. The approach is used for quantitative analysis of oviduct contraction, spatiotemporal characterization of cilia beat frequency and longitudinal imaging. This new approach is a useful in vivo imaging platform for a variety of live studies in mammalian reproduction.      

Microscopic structures of the ovary and female genital ducts of Supachai's caecilian,Ichthyophis supachaii Taylor, 1960 (Amphibia: Gymnophiona)

The structures of the female reproductive system (ovary, oviduct and cloaca) of Ichthyophis supachaii were investigated by dissection, histology and light microscopy. Paired, elongated, sac‐like ovaries are parallel to the gut and fat bodies. Follicle stages include germinal nests of oogonia and primary oocytes, early and late previtellogenic follicles, early and late vitellogenic follicles and atretic follicles. Germinal nests of oogonia comprise oogonia and prefollicular cells. Nests of primary oocytes contain clusters of synchronously developing primary oocytes enclosed by connective tissue. Primary oocytes are associated with follicular cells. Previtellogenic follicles initially form the vitelline envelope, theca cell layers and patches of ooplasmic glycoproteins. Vitellogenic follicles contain heterogeneously sized spherical yolk granules. Atresia is present in several stages of developing follicles. The oviduct is divided into the anterior, middle and posterior parts. All oviductal parts are lined by non‐ciliated epithelium. A small number of mucous cells are present in the middle part. The cloaca of female I. supachaii is divided into the anterior and posterior chambers. The anterior chamber is lined by glandular stratified columnar epithelium, while the posterior chamber has stratified cuboidal epithelium with less mucus production. Our results contribute to useful information on the reproductive biology of caecilians.     

金丝雀输卵管内贮精腺体的组织学及组织化学的研究

本文对产蛋期金丝雀（Ｓｅｒｉｎｕｓｃａｎａｒｉａ）输卵管内的贮精腺体进行了组织学和组织化学观察。结果表明,贮精腺体分布于子宫－阴道交接处阴道一侧长度为０．２１±０．０７ｃｍ区域（以下简称ＵＶ区域）内的固有膜中。该腺体为管状腺,少数具有分枝,由单层柱状上皮细胞构成。腺细胞顶部无纤毛,细胞核排列整齐,位于细胞的基部。贮精腺体呈ＰＡＳ阳性,糖原及酸性粘多糖的含量极微或未能检出。脂类含量较为丰富。酸性磷酸酶活性很高,不含碱性磷酸酶。在组织学及组织化学特征上,ＵＶ区域与毗邻的子宫及阴道区域存在明显差异,贮精腺体细胞与ＵＶ区域粘膜上皮细胞之间的差异也较为显著。     

Ontogenesis of the ovary in a moth midge,Tinearia alternata Say (Diptera: Psychodidae)

In a psychodid, Tinearia alternata, the initial differentiation of the polytrophic ovary occurs during the early larval stages. Early in development, each ovary anlage is a solid organ subdivided into three distinct zones: the cortex houses germ cells and somatic interstitial tissue, while two other somatic regions will give rise to the oviduct calyx and anterior part of the lateral oviduct. Germ cell cluster formation precedes the development of ovarioles. Each ovariole houses only one functional egg chamber. All ovarioles within paired ovaries are developmentally synchronized. In the larval ovaries, the newly formed egg chambers and then the ovarioles are intermingeled with and surrounded by the somatic interstitial tissue of the ovary cortex. The interstitial cells give rise to all the somatic elements of the ovarioles. In the pupal ovaries, the remaining interstitial tissue degenerates; thus, the ovarioles protrude into the body cavity. The ovaries in psychodids develop relatively large and swollen oviduct calyxes that are equivalent to receptaculum seminis (spermatheca). The morphological differentiation of germ cells within the egg chambers starts during late larval/early pupal stages. Nurse cell nuclei contain prominent nucleoli and polytene chromosomes. Oocyte growth results from accumulation of yolk and then, in the final stages of oogenesis, from an inflow of cytoplasm from the nurse cells. J. Morphol. 236:167–177, 1998. © 1998 Wiley-Liss, Inc.     

Studies of the seminal receptacle of the crab Portunus sanguinolentus (Portunidae: Brachyura)

The seminal receptacle or spermatheca of Portunus sanguinolentus consists of two parts--an anterior glandular and a posterior chitinous part. The chitinous part continues as the oviduct, which opens on the sternite of the sixth thoracic segment. Significant morphological and histological differences were observed between the spermatheca, as well as the oviduct, of mated and unmated crabs. In mated crabs the spermatheca is much more bulging, owing to receipt of a copious supply of seminal products, and its cells are hyperactive. Further stages of ovarian development were observed as indicators of sequential changes in the spermatheca. The secretory cells gradually disintegrate by way of holocrine secretion; this results in cellular stratification and the formation of distinct furrows in the chitinous posterior part.