Fertilization Chamber Research Articles

Ultrastructural Study of the Female Reproductive System of Saduria Entomon (Linnaeus, 1758) (Isopoda, Valvifera)

[The structure of the ovaries, oviducts, fertilization chamber and spermathecae of a mature female of Saduria entomon (L., 1758) is presented at the ultrastructural level. In the ovaries a proximal and a distal part is distinguished. The proximal part is only built of a flattened epithelium lying on a thick basal lamina. In the lumen of this part are previtellogenic and primary vitellogenic oocytes enveloped in follicle cells in which synthetic organelles are absent. Previtellogenic oocytes have large nuclei containing synaptonemal complexes and very large nucleoli with vacuoles of various sizes. Primary vitellogenic oocytes are characterized by intra-oocytic yolk formation inside the elements of the endoplasmic reticulum. The walls of the distal parts of the ovaries and oviducts are built of an epithelium and its surrounding muscle cells. On the lumen side, the oviduct epithelium is covered with a cuticle in which an epicuticle and an endocuticle can be distinguished. The fertilization chamber is built of large cells containing bundles of myofilaments in some areas. Their cytoplasm is rich in mitochondria and glycogen granules. The bundles of myofilaments occurring in the muscle cells of the ovaries, oviducts and the cells of the fertilization chamber are striated. They are characterized by a short sarcomer length (2.6 μm and 3.5 μm) and a high ratio of thin-to-thick filaments. The single epithelium building the spermathecae is separated from the haemocoel only by a basal lamina. The apical surface of the epithelium is covered with a thick intima which does not look like a cuticle., The structure of the ovaries, oviducts, fertilization chamber and spermathecae of a mature female of Saduria entomon (L., 1758) is presented at the ultrastructural level. In the ovaries a proximal and a distal part is distinguished. The proximal part is only built of a flattened epithelium lying on a thick basal lamina. In the lumen of this part are previtellogenic and primary vitellogenic oocytes enveloped in follicle cells in which synthetic organelles are absent. Previtellogenic oocytes have large nuclei containing synaptonemal complexes and very large nucleoli with vacuoles of various sizes. Primary vitellogenic oocytes are characterized by intra-oocytic yolk formation inside the elements of the endoplasmic reticulum. The walls of the distal parts of the ovaries and oviducts are built of an epithelium and its surrounding muscle cells. On the lumen side, the oviduct epithelium is covered with a cuticle in which an epicuticle and an endocuticle can be distinguished. The fertilization chamber is built of large cells containing bundles of myofilaments in some areas. Their cytoplasm is rich in mitochondria and glycogen granules. The bundles of myofilaments occurring in the muscle cells of the ovaries, oviducts and the cells of the fertilization chamber are striated. They are characterized by a short sarcomer length (2.6 μm and 3.5 μm) and a high ratio of thin-to-thick filaments. The single epithelium building the spermathecae is separated from the haemocoel only by a basal lamina. The apical surface of the epithelium is covered with a thick intima which does not look like a cuticle.]

The first molluscs ‐ small animals

Abstract Recent data on early Cambrian fossils from various sources suggest that the earliest molluscs up to the conchiferan level of organization were animals of very small (1–2 mm) size. These data are in contrast to current theories on the origin and evolution of molluscan organ systems, most of which postulate an increase of size at the beginning of molluscan evolution. The evolutionary and functional implications and constraints of an original small body size on molluscan locomotion, respiration, excretion and reproduction are discussed. Based on recent fine‐structure work the evolutionary history of the Mollusca is reconsidered. In addition, some alternative ideas are presented to explain the origin of the mantle cavity (originally also used as a fertilization chamber?), ctenidia (originally for ventilation rather than for respiration?), coelom (originally a: gono‐nephrocoel?), and pecularities of the alimentary tract.

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.

Ultrastructural observations on the oviduct, Mehlis' glands and ootype of the monogenean Cichlidogyrus halli typicus (Price & Kirk, 1967) Paperna, 1979

The ancyrocephaline monogenean gill parasite Cichlidogyrus halli typicus has a short oviduct/ovo-vitelline duct separated from the germarium and from the ootype by sphincter muscles. The chamber so-formed contains spermatozoa, the axonemal ends of which appear to be attached in an intimate way between lamellated extensions of the chamber lining. This arrangement may facilitate fertilization by retaining an oocyte temporarily in close contact with the free nucleated ends of the spermatozoa, i.e. the short oviduct/ovo-vitelline duct may serve as a fertilization chamber. There are two distinct types of Mehlis' gland opening at the base of the ootype and the latter has a cellular, non-secretory lining which is not penetrated by gland ducts.

Growth and Development of the Male Gametophyte of Ginkgo biloba within the Ovule (in Vivo)

The mature male gametophyte of Ginkgo biloba can be divided into two regions: a large saccate structure that is suspended within the fertilization chamber above the archegonia, and a pervasive, highly branched haustorial system that ramifies through the intercellular air spaces of the apex of the nucellus. This morphology appears to differ in many ways from the simpler more typical male gametophytes of most other groups of seed plants. Growth and development of the male gametophyte of Ginkgo biloba were studied using computer reconstruction techniques to generate images of the gametophyte from data derived from serial sections through the ovule. These investigations reveal that morphological development of the male gametophyte of Ginkgo biloba is divided into three distinct phases: 1) Germination, characterized by an initial brief period of diffuse growth. This phenomenon has not been described for any other seed plant male gametophyte; 2) Initiation of tip growth and the formation of a tubular body, as typifies all seed plant male gametophytes. In Ginkgo, this is accompanied by a high degree of branching, giving rise to an extensively branched haustorial system; 3) Late swelling of the proximal unbranched portion of the gametophyte resulting in formation of the saccate structure that is characteristic of the mature gametophyte. This process appears to be very similar to late development in cycad male gametophytes. Thus, despite the seemingly anomalous morphology of the mature male gametophyte of Ginkgo biloba, specific patterns of growth and development are in many ways similar to growth processes expressed by the male gametophytes of some or all major groups of seed plants.

GROWTH AND DEVELOPMENT OF THE MALE GAMETOPHYTE OF GINKGO BILOBA WITHIN THE OVULE (IN VIVO)

The mature male gametophyte of Ginkgo biloba can be divided into two regions: a large saccate structure that is suspended within the fertilization chamber above the archegonia, and a pervasive, highly branched haustorial system that ramifies through the intercellular air spaces of the apex of the nucellus. This morphology appears to differ in many ways from the simpler more typical male gametophytes of most other groups of seed plants.Growth and development of the male gametophyte of Ginkgo biloba were studied using computer reconstruction techniques to generate images of the gametophyte from data derived from serial sections through the ovule. These investigations reveal that morphological development of the male gametophyte of Ginkgo biloba is divided into three distinct phases: 1) Germination, characterized by an initial brief period of diffuse growth. This phenomenon has not been described for any other seed plant male gametophyte; 2) Initiation of tip growth and the formation of a tubular body, as typifies all seed plant male gametophytes. In Ginkgo, this is accompanied by a high degree of branching, giving rise to an extensively branched haustorial system; 3) Late swelling of the proximal unbranched portion of the gametophyte resulting in formation of the saccate structure that is characteristic of the mature gametophyte. This process appears to be very similar to late development in cycad male gametophytes.Thus, despite the seemingly anomalous morphology of the mature male gametophyte of Ginkgo biloba, specific patterns of growth and development are in many ways similar to growth processes expressed by the male gametophytes of some or all major groups of seed plants.

Structure, function and evolution of the reproductive system in females of Hebrus pusillus and H. ruficeps (hemiptera, gerromorpha, hebridae).

Females of Hebrus pusillus and H. ruficeps have two ovaries of five telotrophic ovarioles each, two lateral oviducts, a common an intricate sperm storage and delivery system, the gynatrial complex, and a short, tubular ovipositor. The skeletomusculature of this system is fully described in both species and its functions (summarized in Figs. 55-66) reconstructed from study of living bugs, dissections, whole mounts and serial sections. To mate, a male H. pusillus jumps on the back of a female, induces her to lower her ovipositor, and, within 12 min (at 18-24°C), introduces the endosoma of his phallus up its shaft and fills his seminal duct with sperm. The female draws this into her gynatrial sac at the end of copulation and transfers it into her spermatheca in about 30 min (both sperm and spermatheca are longer than the female's body). A single, large egg passes from an ovariole into the vagina where its apex is temporarily lodged in a fertilization chamber. Spermatozoa are drawn from or swim out of the spermatheca into a grooved fecundation canal in the roof of the vagina and forward to the micropyle of the egg. After fertilization, the egg enters the base of the ovipositor and is deposited. The gynatrial complex of female, semiaquatic bugs probably evolved to accommodate the fertilization of the proportionately larger eggs of a lineage of bugs ancestral to Gerromorpha that was being selected for small body size and was then modified to increase the role of the female in controlling fertilization of eggs.

Immunological Studies of the Relationship between the Antigenic Change of Ascaris Oocytes and the Junctional Fluid of the Fertilization Chamber

Antigenic change on the surface of immature oocytes of Ascaris occurred during passage through the oviduct. Using immunodiffusion and immunoelectrophoretic techniques we examined the possible relationship between the antigenic change of immature oocytes and the junctional fluid (JF) which is present in the fertilization chamber. From the immunodiffusion it was found that the anti-immature oocyte serum (A-I serum) had more immunoprecipitation arcs than did the anti-mature oocyte serum (A-M serum) when reacted against the junctional fluid. This indicated that A-I serum contained more immunoglobulins that reacted with junctional fluid than did the A-M serum. This result was substantiated by using immunoelectrophoretic analysis and two dimension crossed immunoelectrophoresis. Our results suggest that during the migration toward the oviduct-uterine junction the immature oocytes might shed surface proteins into the luminal fluid. Alternatively, the membrane surface of mature oocytes may be altered by the interaction with the substances present in the junctional fluid.

Ultrastructure of sperm penetration of house fly eggs

Acrosomes of house fly sperm in the micropyle of eggs were examined and compared with those of sperm in the spermathecae and of sperm in the anterior fertilization chamber of females from which the accessory reproductive glands had been removed. The acrosomal membranes of sperm within the spermatheca and those of sperm in the anterior fertilization chamber of glandless females were intact, and the granular material of the acrosomal cavity was present; those of sperm within the egg micropyle of normal females were lysed and largely devoid of granular acrosomal material. Also, numerous clusters of tubular aggregates were identified within the micropylar cap substance of ovarian eggs and of eggs from glandless females but were greatly disassociated and less abundant in eggs that sperm had penetrated. The various enveloping layers that surround the ooplasm and the immediate consequences of sperm entry of the egg were revealed and documented.

The anatomy of Eubothrium crassum (Bloch) from the pyloric caeca and small intestine of Salmo trutta L.

1. Eubothrium crassum (Bloch) is re-described with additional information about the scolex and genitalia.2. Specific differences between E. crassum and E. salvelini are commented upon and figured.3. The second portion of the uterine duct lying between the central chamber of Mehlis's gland and the uterine sac is established as the “fertilization chamber”.4. Polar bodies and maturation divisions are described and figured in definite relationships with the ovum as evidence of normal maturation in a cestode.5. The position of the receptaculum seminis is determined and a new name, the “vagina sac”, is given to what was previously described as a receptaculum seminis. It is thought to serve for propulsion of male and female cells into the uterine duct.

Sex Studies of Schistosoma japonicum

Sex Studies of Schistosoma japonicum