A Quantitative Analysis of Germ‐cell Loss in Ruminant Seminiferous Epithelium during Meiosis

Wrobel, Karl‐Heinz; Pawar, Harcharan Singh; Schimmel, Margit; Reichold, Jürgen; Gruner, Hannah N.; Kessler, Michael J.

doi:10.1111/j.1439-0531.1994.tb00592.x

Cited by 5 publications

(2 citation statements)

References 21 publications

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“…However, little is known about the exact causes and the beginning of these deteriorations. Germ cell loss occurs naturally during all the three successive steps of spermatogenesis (spermatocytogenesis, meiosis and spermiogenesis) even during the period of maximal seminiferous epithelial activity (Amann 1970;Johnson et al, 198 1, 1983;Paniagua et al, 1987;Wrobel et al, 1994). In older donkeys, the loss rate seems to increase, particularly during the meiotic divisions as well as during spermiogenesis, and is reflected in the significantly lower number of spermatids at the end of sexual maturity.…”

Section: Discussionmentioning

confidence: 99%

A quantitative morphological study of age-related changes in the donkey testis in the period between puberty and senium

Nipken

Wrobel

2009

Andrologia

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The testis of the donkey was used as a model to study age-related changes in the period between puberty and senium. From the age of 1.5 years to the middle of sexual maturity (5 to 6 years) a number of histophysiological features, all indicative of the spermatogenetic efficiency, increase continuously. Then without a longerlasting plateau of maximal performance these features undergo continuous retrogression. Thus, the adult testis is an organ in permanent change. During its progressive period (1.5 to 5 years) the average testicular and tubular volumes treble. The increase in tubular volume is due to an increase in tubular length (from 700 m to 1600 m per testis) and tubular diameter (from 205 pm to 250 pm). Parallel to this growth, the spermatogenetic efficiency of the seminiferous epithelium rises: the number of germ cells entering meiosis increases and the cell loss by apoptosis or exfoliation decreases. During the following regressive period of the testis (5-10 years) seminiferous epithelial height and tubular diameter are again gradually reduced to 70 pm and 205 pm, respectively. The absolute number of Sertoli cells per testis decreases continuously from puberty onwards. The tubular lamina propria thickens with advancing age and at the age of 10 years, displays long irregular projections into the seminiferous epithelium.

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Section: Discussionmentioning

confidence: 99%

A quantitative morphological study of age-related changes in the donkey testis in the period between puberty and senium

Nipken

Wrobel

2009

Andrologia

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“…The ultrastructural changes in the seminiferous epithelium suggest that spermatogenesis was mildly affected [7] as seen in cases of testicular degeneration [1,6,7], with degenerated primary spermatocytes and abnormalities in spermiogenesis. In addition, the presence of numerous intraepithelial spaces at the level where spermatocytes are usually located indicated that the these spermatogenetic stages either died and were then phagocytosed by Sertoli cells or escaped into the tubular lumen [11,12]. The presence of cellular debris in the phago-lysosomes of the Sertoli cells confirmed that some of the germ cells died.…”

Section: Discussionmentioning

confidence: 79%

Morphological Features of the Seminiferous and Cauda Epididymides Epithelia of Breeding Zebu Bulls with Normal and Decreased Testicular Consistency.

Chacón

Müler

Íuez-Martínez

1999

Journal of Reproduction and Development

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Abstract. The fine morphology of the testes and epididymes collected from breeding Zebu (Bos indicus) bulls with normal or decreased testicular consistency (TC) at clinical palpation was studied. The ultrastructure of testicles with a slight to moderate reduction in consistency showed more obvious, albeit slight, degenerative changes in the seminiferous epithelium, with cellular debris present in Sertoli cells, compared with control animals. Abnormalities in the condensation of the chromatin and acrosomes during spermiogenesis were also common findings in cases of decreased TC. The cauda epididymides of these bulls did not show clear morphological deviations compared with controls, although the macrophagic activity of the epithelium was more pronounced, and cell debris as well as foreign cells were apparent in the lumen. The morphological findings confirm the relationship between a decreased TC at clinical palpation and the lowered normality of the testicular parenchyma, thus supporting the value of palpating scrotal contents as part of the field andrological clinical evaluation of breeding Zebu bulls in the tropics. Key words: Testicular consistency, Bos indicus, Ultrastructure, Testis, Epididymis.(J. Reprod. Dev. 45: [119][120][121][122][123][124][125][126][127][128] 1999) eef production in the tropics is based mainly on extensive production systems and natural ity [3] in European breeds under temperate conditions. A decrease in TC is commonly found in connection with acute or sub-acute testicular pathologies, such as testicular degeneration. Attempts to establish a relation between TC and seminal or fertility parameters of Bos indicus bulls have been inconclusive thus far [1,4], although morphological alterations of the seminiferous epithelium were more frequent in Zebu breeding bulls with low TC than in control bulls [5] and were often associated with temperature-induced testicular pathologies [6]. For Bos indicus, Bos taurus and crossbred breeding bulls extensively reared in Costa Rica, a negative relationship was found between decreased B mating. Under these conditions, it is essential that a complete clinical examination of the breeding bulls be made [1] and that clinical parameters related to the fertility of the bull be used as selection criteria for breeding purposes. One of these clinical parameters is testicular consistency (TC), which is normally evaluated while palpating the scrotal contents. Testicular consistency has been shown to be related to conception rate [2] and semen qual-

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Mitotic arrest of female germ cells during prenatal oogenesis. A colcemid-like, non-apoptotic cell death

Wartenberg

Ihmer

Schwarz

et al. 2001

Anatomy and Embryology

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The sequence of events and a possible reason for germ cell death during oogenesis in the prenatal ovary were studied in rat and mouse embryos. ED 14-22 rat and ED 14-16 mouse embryos were studied using semithin sections for light microscopy and serial ultrathin sections for electron microscopy. In addition, the rat material was 3H-thymidine labelled for historadioautography and cytospin preparations of freshly obtained gonads were immunohistochemically analysed. During the transition from the proliferating oogonial stage to the meiotic prophase about 16% of the postmitotic oocytes do not pass the initial meiotic checkpoint on ED 18/19 in the rat (ED 15/16 in the mouse). These germ cells first show structural signs of mitosis; the diploid number of 'super-condensed' chromosomes are globally formed and are concentrated in the center of the cell. Although the germ cells show all morphological signs of living cells they never have mitotic spindles; the micro-tubulus-organisation-centres (MTOCs) are found peripherally and become concentrated, forming a single centrosomal body (acentriolar MTOC) as detected by immunohistochemistry for the centrosomal protein MPM2 and gamma-tubulin. EM studies show 25 nm tubule-like profiles within the MTOC bodies. The centrioles frequently lie separate from the MTOC material or are not present at all; the germ cells are apparently arrested in a prophase- or metaphase-like stage when they have reached the postmitotic G2/preleptotenal transition and are unable to enter meiosis. Forty-eight to 72 h after the first mitotically arrested germ cells are found, degeneration is seen in these germ cells. This second event, the germ cell death proper, shows neither criteria of apoptosis (cell shrinkage, marginal condensation of chromatin, DNA fragmentation) nor signs of necrosis (cell swelling, pycnosis, inflammation). Both arrested pro- and metaphase-like stages are found with signs of cell death and phagocytosis. The morphological signs of phagocytosis are found in neighbouring pregranulosa cells. The final heterocytotic bodies contain the remnants of the centrosomal (MTOC) material and DAPI-positive DNA material. The pregranulosa cells are mitotically silent during the phase when mitotic arrest and germ cell degeneration is found. The results suggest the presence of a hypothetical 'anti-spindle' factor, which under normal conditions is necessary for induction of meiotic prophase. The structural events of 'arrested mitosis' is reminiscent of those induced by the antimitotic, tubule-degrading drug colcemid. This type of arrest may inhibit meiosis of more than 33% prenatal germ cells and induce their cell death.

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A Quantitative Analysis of Germ‐cell Loss in Ruminant Seminiferous Epithelium during Meiosis

Cited by 5 publications

References 21 publications

A quantitative morphological study of age-related changes in the donkey testis in the period between puberty and senium

A quantitative morphological study of age-related changes in the donkey testis in the period between puberty and senium

Morphological Features of the Seminiferous and Cauda Epididymides Epithelia of Breeding Zebu Bulls with Normal and Decreased Testicular Consistency.

Mitotic arrest of female germ cells during prenatal oogenesis. A colcemid-like, non-apoptotic cell death

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