Cyclic changes in the testis of the brook stickleback Eucalia inconstans (Kirtland)

Abstract

The cyclic changes in the testis of the five-spined stickleback Eucalia inconstans (Kirtland) were studied histologically. Specimens were trapped between July 1965 and July 1967 in a shallow pond near London, Ontario.A three-dimensional microscopic study showed a main vas deferens and a system of primary, secondary and tertiary tubules.The testis cycle was divided into seven arbitrary stages. Spawning takes placc from mid-April to mid-July. This is followed by the division of primary spermatogonia which are located along the walls of the tubules, producing cysts of spermatogonia enclosed i n connective tissue which is surrounded by a thin epithelium. Both primary and secondary spermatocytes develop within these cysts. Breakdown of the cysts occurs with the development of spermatids and spermiogenesis occurs while spermatids are free in the tubules. Over-wintering of mature sperm takes place. Development of mature sperm from primary spermatogonia takes about 156 days.Germinal epithelium is absent but primary germ cells are believed to be those cells occupying the spaces between the tubules o f the testis. No tissue which might be implicated in hormone production was observed.Phagocytic invasion of the testis has been studied. Massive infiltration by phagocytes is believed to be responsible for the sudden increase in testis weight observed during spawning. These cells ingest sperm nuclei and groups of them have been observed in the lumen of the tubules and the vas deferens, probably on their way out of the body.The present paper is a histological study of the testicular cycle of Eucalia inconstuns (Kirtland) (Osteichythes: Gasterosteidae), the five-spined stickleback. It includes a stereoscopic description of the arrangement of the ducts and tubules; a study of cyst formation and structure in spermatogenesis; and an investigation by phase and ordinary light microscopy of the origin, activity, function, and fate of the phagocytes which invade the connective tissue of the testis.Earlier histological investigations of the teleostean testis have been mainly restricted to cyclic changes. Among the earlier workers was Turner ~('19) who outlined the seasonal cyclic changes in Perca flnvescens. Weisel ('43) attempted to trace correlations which might exist between the histology of the testis and the peculiar life history of the salmon Oncorhynchus nerlza which dies after the first spawning. Matthews ('38) spermatogenesis in Umbra limi, the mudminnow, with special reference to the behaviour of the spennatogonial chromosomes and the first maturation division. James ('56) described the histology of gonad changes in the blue gill Lepomis macrochirus, and the largemouth bass Huro salmoides. One of the more recent studies in teleosts was by Henderson ('62) who studied the annual cycle in the testis of the eastern brook trout Salvelinus fontinalis and made some preliminary observations in connection with the possible localization of endocrine tissue in the testis.In 1967, Braekevelt and McMillan described the ovarian...

Hybrid Male Sterility between the Fresh- and Brackish-water Types of Ninespine Stickleback Pungitius pungitius (Pisces, Gasterosteidae)

“…Histology indicated that a large number of tubules contained cysts with spermatocytes in the hybrid males, but only a small number of such tubules located near the outside of testis in the controls. In a closely related gasterosteid fish, brook stickleback ( Culaea inconstans ), spermatocyte formation completed in the first autumn of life, and most of the cysts filled with spermatocytes broke down prior to the winter season for spermiogenesis (Ruby and McMillan, 1970). Taking into account the similarity in the life cycles between the brook and ninespine sticklebacks (Ruby and McMillan, 1970;Goto et al ., 1979), the present result for hybrid males suggested delay or arrest of spermatogenesis reducing the number of spermatids and distorting their shape.…”

“…After embedding in paraffin, the entire gonad was sectioned transversally at 8 µ m thickness and stained with Delafield's hematoxylin and eosin according to the standard procedures. Histological nomenclatures followed Ruby and McMillan (1970).…”

Aspects of the reproductive biology of the southern mullet,Liza richardsoni, from Algoa Bay, South Africa

“…Testicular maturation was assessed using the classification system based on the presence and relative proportions of the various spermatogenic cells. Such schemes have been adopted by Gokhale (1957), Hyder (1969, Hiroi & Yamamoto (1970), Ruby & McMillan (1970 and . Figure 2 shows monthly variations in gonadosomatic indices.…”

The Structure of the Testis of the Mullet,Liza Dumerili(Teleostei; Mugilidae) With Special Reference to Spermatogenesis

“…In Engraulis malabaricus, Punctus co/us (Desphandi & Nadkarni 1973), Euca/ia inconstans (Ruby & McMillan 1970) and salmonids (Henderson 1967), the main sperm ducts are short and extend superficially from the posterior parts of the testes, unlike those found in L dumerili and probably other Mugilidae. Apart from this and other minor differences, the position and macro-appearance of the testes of L. dumerili are very similar to those of other teleosts.…”

“…Each testis is suspended by the mesorchium, which is continuous with the visceral peritoneum of the swim-bladder and which runs along the entire length of the testes, as in Eucalia inconstans (Ruby & McMillan 1970). The left testis is always the longer of the two and extends anteriorly to the middle cardiac part of the stomach, to which it is attached by connective tissue.…”