Scanning and transmission electron microscopic analysis of ampullary segment of oviduct during estrous cycle in caprines.

The ampullary segment of the mammalian oviduct provides suitable milieu for fertilization and development of zygote before implantation into uterus. It is, therefore, in the present study, the cyclic changes in the morphology of ampullary segment of goat oviduct were studied during follicular and luteal phases using scanning and transmission electron microscopy techniques. Topographical analysis revealed the presence of uniformly ciliated ampullary epithelia, concealing apical processes of non-ciliated cells along with bulbous secretory cells during follicular phase. The luteal phase was marked with decline in number of ciliated cells with increased occurrence of secretory cells. The ultrastructure analysis has demonstrated the presence of indented nuclear membrane, supranuclear cytoplasm, secretory granules, rough endoplasmic reticulum, large lipid droplets, apically located glycogen masses, oval shaped mitochondria in the secretory cells. The ciliated cells were characterized by the presence of elongated nuclei, abundant smooth endoplasmic reticulum, oval or spherical shaped mitochondria with crecentric cristae during follicular phase. However, in the luteal phase, secretory cells were possessing highly indented nucleus with diffused electron dense chromatin, hyaline nucleosol, increased number of lipid droplets. The ciliated cells had numerous fibrous granules and basal bodies. The parallel use of scanning and transmission electron microscopy techniques has enabled us to examine the cyclic and hormone dependent changes occurring in the topography and fine structure of epithelium of ampullary segment and its cells during different reproductive phases that will be great help in understanding major bottle neck that limits success rate in vitro fertilization and embryo transfer technology.

Topographic and ultrastructural variations in isthmus segment of oviduct during oestrous cycle in Caprines.

In the present study, the morphological variations in the isthmus segment of goat (Capra hircus) oviduct were studied using scanning and ultrastructural techniques during luteal and follicular phases of oestrous cycle. Topographic analysis of the isthmus epithelium in the follicular phase demonstrated irregular distribution of ciliated cells on the epithelium. A few secretory cells possessed bulbous apical processes which were concealed by the cilia. Cyclic changes were noticed in the secretory cells of isthmus. Under electron microscopy the isthmus region of the oviduct during the follicular phase revealed presence of almost blunt processes at their apical surfaces. The secretory cells were attached to the basal lamina and were characterized by the presence of secretory granules, numerous ribosomes, extensive smooth endoplasmic reticulum, well-developed golgi zones in the cytoplasm, and a microvillus luminal surface. The parallel use of these two methods in isthmus segment of the oviduct has enabled us to analyze the marked cyclic variations in the topography and fine structure during follicular and luteal phases of the oestrous cycle. The results of the present investigation on topography and ultrastructure will be of great help in explaining different bottlenecks of gamete interaction, maturation, fertilization, and early embryo development.

Scanning electron microscopic changes in granulosa cells during follicular atresia in Caprine ovary.

During this study, topographic changes in healthy and atretic granulosa cells have been investigated during follicular atresia in goat ovary. Under scanning electron microscopy atresia was marked by asymmetrical shrinkage and vacuolization of cytoplasm. The specific topographical alterations observed in atretic cells were loss of micro extensions, disruption of cell-cell interaction, and smooth-textured membrane with a number of uneven depressions and ruffles. Some portions of the cell membrane were marked by extensive shrinkage due to condensation of cytosol. Irregular membrane at occasions was studded with blunt microextensions. The findings of present investigation will help in understanding the cellular changes in granulosa cells during follicular atresia and will find applications in screening of follicles for in vitro culture, in vitro fertilization and Embryo transfer technology.

Ultrastructural characterization of apoptotic granulosa cells in caprine ovary.

The unique phenomenon of cell proliferation and apoptosis is encountered in the ovarian follicles undergoing early stages of atresia. The aim of this study was to verify the morphological variations in these two physiologically distinct processes operating in antral follicles of caprine ovaries using histological and ultrastructural techniques. Histologically the degenerating granulosa cells were characterized by condensed cytoplasm, and nucleus fragmentation in hazy cytosol. The pyknotic nuclei of degenerating cells stained darkly with haematoxylin and giemsa while the cytoplasm was eosinophilic. Under electron microscopy, apoptosis was marked by asymmetrical shrinkage, vacuolization of cytoplasm, swollen and vacuolated mitochondria, increased irregularity and/or fragmentation of nucleus, chromatin condensation and finally, production of membrane enclosed nuclear fragments containing intracellular material, the apoptotic bodies. The parallel use of these two methods on caprine ovaries has enabled us to analyse the decline in the frequency of granulosa cells during follicular atresia due to apoptosis.