Record Details
The fine structure of spermatid differentiation in the mussel, Mytilus edulis, Linn
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | The fine structure of spermatid differentiation in the mussel, Mytilus edulis, Linn |
| Names |
Longo, Frank J., 1939-
(creator) Dornfeld, E. J. (advisor) |
| Date Issued | 1967-04-14 (iso8601) |
| Note | Graduation date: 1967 |
| Abstract | The spermiogenesis of Mytilus edulis (a marine mussel) has been studied, employing techniques of light and electron microscopy and cytochemical preparations. The observations trace the development of the acrosomal complex, the nucleus, the mitochondrial middle-piece, and the flagellum. In early spermatids numerous membrane-bounded proacrosomal vesicles arise from several Golgi complexes and coalesce to form a single large acrosomal vesicle. This comes to rest on the anterior surface of the nucleus and invaginates to become an elongated cone-shaped structure. An electron dense, spherical mass of membranoid sleeve material, also arising from the Golgi complex, adjoins the acrosomal vesicle and later occupies its indentation. In mature spermatozoa the membranoid sleeve lines the cavity of the cone-shaped acrosomal vesicle and surrounds the axial rod. Precursor material of the axial rod is first observed between the nucleus and the acrosomal vesicle as an aggregation of fibers. This later extends posteriorly into the nucleus and anteriorly into the cavity of the acrosomal vesicle. In the mature spermatozoon the fibrous axial rod ends posteriorly in the centriolar region of the middle-piece. The endoplasmic reticulum of early spermatids is a rudimentary system of membrane-bounded canaliculi and flattened vesicles which is predominantly free of ribosomes. Independent or clustered ribosome-like particles are present in the ground cytoplasm. By late spermiogenesis the reticulum has largely disappeared and the ground cytoplasm containing a dense particulate aggregate is sloughed off. In the early spermatid a dense filamentous network of chromatin in the interior and along the periphery of the nucleus increases in size by accretion of the finer karyoplasm. Eventually the interaggregate spaces are obliterated as the large, coarsely granular masses coalesce to form the compact, barrel-shaped nucleus of the sperm. By mid-spermiogenesis the randomly distributed elipsoid mitochondria become localized around the nucleus. The association with the nucleus is intimate and in many cases the mitochondria may be found in shallow recesses with the nuclear envelope reflected over their surface. Subsequently the mitochondria became spheroid, reduced to five in number, and restricted to the sperm middle-piece. Two cylindrical centrioles are situated near the base of the nucleus and are surrounded by the mitochondria of the middle-piece. The distal centriole elongates and from it the longitudinal fibrils of the sperm flagellum originate. The proximal centriole, oriented obliquely to the distal centriole, retains its initial structure. Tests with Sudan black B showed the presence of phospholipids in the mitochondria of late spermatids and mature sperm. Cytochemical techniques for carbohydrates indicated a neutral mucoprotein for the proacrosomal vesicles and allowed these to be identified in early spermatogenesis. The development of the Mytilus spermatid was compared with that of other vertebrate and invertebrate species. |
| Genre | Thesis/Dissertation |
| Topic | Spermatogenesis |
| Identifier | http://hdl.handle.net/1957/47217 |
