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Ultrastructural and histochemical observations on electroejaculated spermatophores of the palaemonid shrimp,
W J Dougherty1, M M Dougherty, S G Harris
1Department of Anatomy and Cell Biology.,Medical University of South Carolina, Charleston, South Carolina 29425, USA.
Abstract:
Spermatophores obtained by electroejaculation from mature males of Macrobrachium rosenbergii were studied by light microscopy and by transmission and scanning electron microscopy. Upon electrical stimulation, single spermatophores were usually extruded simultaneously from each gonopore and frequently became firmly adherent to one another forming a compound spermatophore. Individual spermatophores were pod-shaped. 0.5-1 cm long, 2-3 microm in diameter and consisted of a lateral sperm mass, a medial mucus mass, and a noncellular capsule. The capsule was a single-layered PAS-reactive structure composed of fine, intertwining fibrils and almost completely surrounded the sperm and mucus masses. On its outer surface were large. AB-reactive globules of flocculent material partially surrounded by finger-like extensions of a canaliculated reticulum composed of fine, intertwining fibrils. The canaliculated reticulum may permit fluid imbibition by the spermatophore. Forming a central band within the capsule were many small membrane-less AB/PAS-reactive granules. The lateral sperm masses consisted of unistellate spermatozoa embedded in an AB/PAS-reaetive matrix composed of globules of flocculent. AB-reactive material and a highly plastic canaliculated and thread-filled reticulum. The reticulum itself consisted of fine, intertwining fibrils. The threads within the interstices of the reticulum were long, curving structures, 30-36 nm in diameter. The function(s) of the canaliculated and thread-filled reticulum within the sperm mass is not known at this time. The medial mucus mass was similar in fine structure and histochemical reactivity to the sperm mass, except that spermatozoa were lacking. It is apparent that the spermatophore of M. rosenbergii consists of relatively few complexly arranged structural and macromolecular components designed to transport and protect the spermatozoa.
Insights
The study details the complex structure of Macrobrachium rosenbergii spermatophores, revealing intricate components designed for sperm transport and protection. These findings enhance our understanding of crustacean reproductive biology.
Area of Science:
- * Aquatic biology
- * Reproductive biology
- * Microscopy and ultrastructure
Background:
- * Spermatophores are crucial for sperm transfer in many aquatic invertebrates.
- * The giant freshwater prawn, Macrobrachium rosenbergii, is an economically important aquaculture species.
- * Detailed ultrastructural analysis of M. rosenbergii spermatophores is limited.
Purpose of the Study:
- * To elucidate the detailed ultrastructure and composition of spermatophores from M. rosenbergii.
- * To identify the structural and macromolecular components involved in sperm protection and transport.
Main Methods:
- * Spermatophores were obtained via electroejaculation from mature M. rosenbergii males.
- * Light microscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were employed.
- * Histochemical staining (PAS and AB) was used to identify macromolecular components.
Main Results:
- * Spermatophores are pod-shaped, approximately 0.5-1 cm long and 2-3 microm in diameter.
- * Each spermatophore comprises a capsule, a lateral sperm mass, and a medial mucus mass.
- * The capsule contains PAS-reactive fibrils, AB-reactive globules, and a canaliculated reticulum; sperm masses feature spermatozoa within a matrix of similar components and a unique thread-filled reticulum.
Conclusions:
- * The M. rosenbergii spermatophore possesses a complex, multi-component structure.
- * These components are intricately arranged to ensure efficient transport and protection of spermatozoa.
- * The study provides foundational ultrastructural data for understanding prawn reproductive mechanisms.
