Sites of lanthanum occlusion in the testis of the crayfish Procambarus paeninsulanus (Crustacea: Cambaridae).

The presence of stage-dependent occlusive junctions between adjacent Sertoli cells in the seminiferous epithelium of the crayfish testis was demonstrated by a lanthanum tracer study. The germinal epithelium did not appear to be compartmentalized, as evidenced by access of lanthanum to spermatogonia, spermatocytes, and spermatids. During late spermiogenesis, when encapsulated stage VI spermatids were concentrated in the center of an acinus, lanthanum was excluded apically, coincident with lumen formation. This is the first study examining occluding junctions using a barrier penetration method in the testis of a crustacean.

The effect of prostaglandin E2 and prostaglandin F2 alpha on ovarian tissue in the Florida crayfish Procambarus paeninsulanus.

Prostaglandins are oxygenated fatty acid derivatives of arachidonic acid involved in a number of vertebrate and invertebrate reproductive processes. While the role of prostaglandins in vertebrate reproduction has been well established, their function in the invertebrate has not been investigated extensively. The purpose of this study was to investigate the effect prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) on ovarian tissue in the crayfish Procambarus paeninsulanus. PGF2 alpha induced contraction of ovarian tissue in a dose-dependent manner, while PGE2 alpha had little effect. Incubation of ovarian tissue with PGF2 alpha also produced a dose-dependent increase in cAMP. In addition, the experimental technique of back-phosphorylation, in which exogenously added cAMP-dependent protein kinase is able to transfer phosphate to previously non-phosphorylated proteins, revealed that PGF2 alpha-induced increases in cAMP resulted in the specific phosphorylation of a 45 kDa protein. These data give evidence that PGF2 alpha may be involved in crustacean ovulation by causing the cAMP-mediated contraction of ovarian tissue and that this contraction may involve the phosphorylation of proteins associated with the cytoskeleton.

The role of sertoli cells in spermatid maturation in the testis of the crayfish, Procambarus paeninsulanus.

With the onset of spermiogenesis, many changes become apparent in the crayfish spermatid during its transition to mature sperm. The nucleus passes through a series of stages, excess cytoplasm is removed, the acrosome develops, and nuclear arms form and become wrapped around the sperm prior to its enclosure in a capsule. Changes are also apparent in the Sertoli cells surrounding the germ cells in the crayfish testis. The amount of cytoplasm of individual Sertoli cells appears to increase in quantity and changes in the intracellular organelles become apparent. As spermiogenesis commences, the cytoplasm along one side of Sertoli cells adjacent to the spermatids is devoid of obvious organelles. Numerous finger/like projections of Sertoli cytoplasm penetrate into the spermatid and appear to isolate portions of the sperm cytoplasm. During later stages of spermiogenesis, several vesicles in the Sertoli cells which appear to contain droplets of this isolated sperm cytoplasm. appear to undergo lytic changes, As the amount of cytoplasm of the spermatid is reduced, contact is maintained between the spermatid and Sertoli cell in the area of the acrosome. The nuclear arms of the sperm extend into the Sertoli cell during their formation and later become wrapped around the acrosomal area of the sperm. At this time, very little space exists between the Sertoli cell and its many sperm. Large vesicles of electron dense material appear to be released by the Sertoli cells into the space between the sperm and Sertoli cell. This material completely surrounds the sperm and forms the sperm capsule. Spermiation involves the gradual dissolution of the points of contact between the sperm capsule and the Sertoli cell.

Ultrastructure of spermatogonia, spermatocytes, and sertoli cells in the testis of the crayfish, Procambarus paeninsulanus.

The testes of the crayfish, Procambarus paeninsulanus, were prepared for light and transmission electron microscopy. During early stages of spermatogenesis, when the spermatogonia are dividing, processes from a single Sertoli cell extend between numerous spermatogonia. As the cells enter meiosis, many points of contact can be observed between the Sertoli cell processes and spermatocytes. These desmosome-gap junctions are maintained between the germ and Sertoli cells until the early spermatid stage.

Changes in prostaglandin E2 and F2 alpha during vitellogenesis in the Florida crayfish Procambarus paeninsulanus.

While the role of eicosanoids in reproduction in vertebrate species has been well established, the role of these fatty acid derivatives in invertebrate species has not been as well characterized. The purpose of this study was to investigate changes in prostaglandins E2 and F2 alpha during vitellogenesis in the crayfish Procambarus paeninsulanus. In homogenates of crayfish ovaries taken at various stages of development, the rate of prostaglandin synthesis and the concentrations of prostaglandins E2 and F2 alpha increased during the final stages of yolk production just prior to ovulation. A gradual increase in prostaglandin E2 amounts was observed throughout the progression of vitellogenesis. The data suggests the possible involvement of prostaglandins in regulatory events associated with vitellogenesis and the induction of ovulation in Procambarus paeninsulanus.

Junctional complexes between the Sertoli cells in the testis of the crayfish,Procambarus paeninsulanus.

The testis of the crayfish,Procambarus paeninsulanus, was prepared for light and electron microscopic study. It is composed of tubules containing germ-spermatogenic and somatic-Sertoli cells. In sections of tubules lacking sperm, the Sertoli cells rest on the basement membrane. A desmosome-like junction is found near the luminal surface between two adjacent Sertoli cells. It is closely associated with a long, septate junction. Between Sertoli cells which have surrounded numerous spermatids, the undulating membranes exhibit profiles of pleated septate junctions in tangential sections. The morphology of the pleated septate junctions between adjacent Sertoli cells suggests a possible role as a permeability barrier.

Structure of the female reproductive tract of the apple snail. II. Scanning electron microscopy.

The albumen gland of Pomacea paludosa, a prosobranch gastropod, contains two main ducts. The albumen gland duct consists of a single layer of secretory and non-secretory cells. The surface of the non-secretory cells is covered with cilia. Microvilli are associated with the luminal edges of the secretory cells. Globules of secretory products appear at the cell surfaces. The capsule gland duct coils through the albumen gland and is composed of two opposing faces each of two layers of cells. The upper layer consists of ciliated non-secretory cells and the microvilli covered necks of the goblet-shaped secretory cells. The bases of the secretory cells comprises the lower layer of cells. Differences in the arrangement of cellular processes and number exists between the duct epithelia.

Spermiogenesis in a hermit-crab, Coenobita clypeatus. II. Sertoli cells.

The testes of the land hermit crab, Coenobita clypeatus, contains germinal cells and non-germinative cells. The latter function in the manner of the vertebrate Sertoli cells in apparently providing nourishment, support and possibly hormones during spermiogenesis. Each Sertoli cell surrounds several germinal cells. The mitochondria, rough and smooth endoplasmic reticulum and Golgi apparatus show changes in structure when in contact with germinal cells in different stages of spermiogenesis. These changes are suggestive of active synthesis and metabolism of cellular products(s).

Intersexes in the dog.

A litter of five salukis was presented in which all of the individuals were intersexes or hermaphrodites. Anatomical abnormalities were observed. The external genitalia resembled a combination of penile sheath and vulva positioned approximately midway between the anus and umbilicus. At birth structures resembling scrotal sacs were present on either side of the genital structure. These were not apparent in older animals. Internal anatomy consisted of two gonads in a position expected for ovaries, oviducts, uterus and cord-like structures lateral to the uterus which extended from gonad to inside of the "scrotal sacs." Histologically, the gonads appeared to be ovaries which contained many dysgenic follicles. Cause of the condition is unknown.

Vitellogenesis stimulated by thoracic ganglion implants into destalked immature spider crabs, Libinia emarginata.

Since destalked immature female Libinia emarginata fail to molt to maturity (Hinsch, 1972) and implants of thoracic ganglion of adult females into young females of Potamon dehaani caused a doubling of ovarian weight and differentiation of yolk granules (Otsu, 1963), the effects of the thoracic ganglion implantation on sexual maturation in Libinia was investigated. Destalked immature Libinia with a maximum carapace length of 4-5 cm received two implants of adult female thoracic ganglion at 10-day intervals. All of the surviving experimental animals and destalked controls molted to immaturity. Most of the experimental animals failed to complete a successful molt and few survived longer than 3-4 days. The experimental animals that survived for over a week showed signs of yolk deposition not observed in the destalked controls. Eggs in several stages of vitellogenesis were scattered throughout the gonad in the animal showing the most pronounced effect. This was not observed in any of the destalked controls.

Glassy particles in lunar fines.

Most of the Apollo 11 glassy particles differ from those generated by terrestrial volcanism, by meteoritic impacts, or by the condensation of the parent bodies of meteorites. Some of the particles may have been formed by the action of solar flares on the lunar surface.

Ultrastructural observations of vitellogenesis in the spider crab, Libinia emarginata L.

Ovaries from the spider crab, Libinia emarginata L. were studied to learn more of vitellogenesis in crustaceans. Oogonia and previtellogenic oocytes were found in the core of the ovaries. Vitellogenic oocytes are located more peripherally. Profiles of the endoplasmic reticulum are abundant in the vitellogenic oocytes. The granular and agranular reticulum as well as the Golgi complex are active in yolk synthesis. As vitellogenesis proceeds, yolk precursors are incorporated into the egg by micropinocytosis at the egg surface. Thus, in Libinia, yolk materials appear to be derived from both intra- and extraoocytic sources.