Morphology, histochemistry, and biochemistry of human oogenesis and ovulation

Immunolocalization of zona pellucida antigens in the ovarian follicle of dogs, cats, horses and elephants

A comparative evaluation of the location of immunoreactive porcine zona pellucida (pZP) glycoproteins was performed with polyclonal rabbit anti-pZP antibodies on ovarian sections of the dog, cat, horse, and elephant. For this, formalin (light microscopy) and glutaraldehyde (transmission electron microscopy [TEM]) fixed ovarian sections were incubated with antibodies raised against highly purified pZP. Staining patterns were determined with diaminobenzidine (DAB) at the light level. The dog ZP had a distinct staining distribution that is characterized by intense staining around the periphery of the ZP and the oolemma and less dense staining throughout the width of the ZP. In dog follicles that contained multiple oocytes, there were oocytes of identical and dissimilar stages. Cat ovarian sections showed uniform staining of the ZP. Horse results showed uniform staining of ZP and ooplasm, and granulosa cells (GC). Elephant sections showed staining of the ZP with dense staining at the oolemma, as well as staining of the ooplasm. In all species the staining of the ZP was not evident until GC differentiation. In all cases there was no staining of ovarian tissue with control normal rabbit serum. Specific staining patterns of ZP were evaluated by TEM and immunogold staining. The immunogold-linked anti-pZP antibodies stained the ZP matrix in all species. There was staining of ooplasm organelles suggesting that ZP secretion originates from the oocyte of the dog and cat. In addition, follicular and ZP measurements were taken that allowed accurate characterization of follicle stage. These findings suggest that in all four species the ZP is recognized by anti-pZP antibodies and there is also evidence to suggest the possible origins of ZP glycoproteins.

Possible mechanisms of mammalian immunocontraception

Ecological and conservation programs in ecosystems around the world have experienced varied success in population management. One of the greatest problems is that human expansion has led to the shrinking of wildlife habitat and, as a result, the overpopulation of many different species has occurred. The pressures exerted by the increased number of animals has caused environmental damage. The humane and practical control of these populations has solicited the scientific community to arrive at a safe, effective, and cost-efficient means of population control. Immunocontraception using zona pellucida antigens, specifically porcine zona pellucida (pZP), has become one of the most promising population control tools in the world today, with notable successes in horses and elephants. A conundrum has risen where pZP, a single vaccine, successfully induces an immunocontraceptive effect in multiple species of mammals. This review describes the most current data pertaining to the mammalian zona pellucida and immunocontraception, and from these studies, we suggest several potential mechanisms of immunocontraception.

Extraction and quantification of acrosin, beta-N-acetylglucosaminidase, and arylsulfatase-A from equine ejaculated spermatozoa

Acrosin, Arysulfatase A, and beta-N-acetylglucosaminidase are three key enzymes localized within the mammalian acrosome that play a pivotal role in the penetration of the oocyte. The objectives of this study were to compare two methods of enzyme extraction based on the activities of these enzymes from equine spermatozoa. Method A utilized a 0.5 M Tris-maleate buffer containing 0.1% Triton X-100 and Hyamine 2389. Method B used 0.05 M Tris-HCl, 0.05 M MgCl2 in 0.05 M Tris-maleate, followed by 0.05 M Tris-maleate containing 0.1% Triton X-100. Results indicated that acrosin was initially bound in an acrosin-acrosin inhibitor complex; this complex was dissociated after incubating the extract in 2 mM HCl. Significant (P < 0.001) increases in acrosin activity were found after-acid extraction from 0.076 U/mg after Method B to 0.327 U/mg after Method A. Arylsulfatase A activity was found to have a higher mean activity (P < 0.03) after Method A (0.012 U/mg) as opposed to Method B (0.007 U/mg). Similarly, beta-N-acetylglucosaminidase was found to have a higher mean specific activity (P < 0.001) after Method A (0.037 U/mg) as compared to Method B (0.008 U/mg). This is the first report of the quantification of these enzymes from equine spermatozoa which can ultimately be used as an index of acrosomal damage in cryopreserved semen, and provide additional insight into biochemical alterations between normal vs. abnormal semen.

Antigens in bovine estrual and cystic follicles

The antigenic spectra of estrual or cystic follicular fluid (FF) consisted of 11 blood serum antigens while that of estrual or cystic ovary consisted of 9 identical antigens of which 2 were ovarian specific. The two ovarian-specific antigens were detected with antisera to estrual or cystic ovary but not with antisera to nonestrual ovaries. They were in higher concentration in estrual ovary than cystic ovary, were localized in bovine oocyte zona pellucida by immunofluorescence and light scattering, and cross-reacted with prostate tissue. Cystic FF contained a higher concentration (P less than 0.05) of IgG than at any stage of the cycle except estrus, and a lower concentration (P less than 0.05) of estradiol-17 beta than at estrus. It was hypothesized that increased levels of estradiol during estrus alter the permeability of the follicle wall unmasking a zona pellucida antigen in the preovulatory follicle. The appearance of this previously unexposed antigen at estrus could lead to an inflammatory-like response triggering ovulation.

The cellular origin of the zona pellucida antigen in the human and hamster

The origin of the zona pellucida in follicles at different stages of maturation was studied in the hamster and human by indirect immunofluorescence microscopy using a specific anti-hamster zona pellucida serum. The earliest detection of the zona pellucida material occurred in the ooplasm of oocytes in primordial follicles. In primary follicles, the fluorescence was localized at the periphery of the oocyte. In secondary and in mature follicles a deposition of fluorescent material was visualized on the inner and outer regions of the zona pellucida. Follicular cells, other than the oocyte, failed to exhibit a fluorescent reaction with the antizona pellucida serum. It is concluded that the oocyte is an important source of the antigenic material of the zona pellucida of hamster and human ova.

Morphological and histochemical observations on the ovarian balls of Centrorhynchus corvi (Acanthocephala)

Unlike in other acanthocephalans, the overian balls of Centrorhynchus corvi are complex and are composed of 24–30 ovarian ball units. Each ovarian ball unit consists of three structural and functional units – the oogonial syncytium, developing oogenetic cells and the supporting syncytium – complementary to the ovarian balls of other acanthocephalans. Three metamorphic stages of the nuclei in the oogonial syncytium are described, depending on the nuclear morphology, chromatin structure and appearance of the nucleolus. Third-stage nuclei bulge out at the periphery of the oogonial syncytium and are surrounded by its cytoplasm and a thin membrane. Ultimately these are separated from the oogonial syncytium to from oogonia containing small amounts of cytoplasmic components derived from the oogonial syncytium. Nuclei of the young oogonia, oognia at the budding stage, and 3rd-stage nuclei of the oogonial syncytium all possess nucleoli and are similar also in their nuclear dimensions and cytochemical affinities. Nuclear resemblances, and cytoplasmic similarities of the oogonia and oogonial syncytium with regard to the presence of lipids, RNA and proteins support the concept of the origin of oogonia from the oogonial syncytium.

The free oogonia divide mitotically in the cellular zone where they undergo a single mitotic division and the resulting oocytes enter the prophase of meiosis. I. The meiotic primary oocytes in contrast to the permeiotic primary oocytes of other acanthoscephalans enter the growth phase which is closely accompanied by the accumulation of various ooplasmic components such as basophilic yolk nucleus which is composed of RNA, proteins, lipoproteins and phospholipids. Histochemical features of the oogonial and supporting syncytium are described.

Immunological aspects of sperm receptors on the zona pellucida of mammalian eggs

Sperm receptor sites on the surface of the zona pellucida are believed to be necessary for fertilization on the mammalian egg. Ovary specific antibodies are known to precipitate the zona pellucida and are also responsible for inhibition of sperm binding and subsequent fertilization. The nature of the proposed receptor sites which are blocked by antibodies are discussed relative to comparable studies in which phytoagglutinins and other agents are used to determine the chemical nature of sperm receptor sites.