Testis parenşiminin, seminifer tubulün sıralı hücreleri ve onların kanalları ile interstisyal hücrelerden oluştuğu gözlendi. Sertoli hücrelerinin tubulün bazal laminası üzerinde olduğu saptandı. Bunların az sayıda olduğu ve tubul boyunca aralıklı olarak dizildikleri tespit edildi. Sitoplazmaları farklı şekillerde çok sayıda mitokondriye sahipti. Leydig hücreleri büyük ve asidofilik hücrelerdi. Spermatogonia, yoğun kromatinli büyük, yuvarlak veya oval bir çekirdekle karakterize idi. Primer spermatositler, seminifer tubul içinde görülen en büyük germ hücreleriydi. Spermatid'in apikal başı sertoli hücre sitoplazmasına girmişti.

The light and electron microscopic structure of the normal testis has been described in several species: human ^3-5, rat ^{6, 7,} rabbit ^{8, 9,} dog ^{10, 11}. However, there was no study on the histologic structure of testis in badger.

Therefore, this study was focused on the investigation of the histology of testis in adult badgers to make a contribution to knowledge in this field.

The purpose of this study was to examine, with the light and TEM, the structure of testis in adult badger, in order to compare the results with those previous reports in other rodentia.

Light Microscopy: Under penthotal-induced (6 ml/kg) anaesthesia, the testes were removed. Samples of testes were fixed in Bouin's solution. Tissue samples were routinely processed through a graded series of alcohols, cleared in xylol and embedded in parafin. 7 µm thick sections were obtained and stained with haematoxylin and eosin and PAS.

Electron Microscopy: Pieces of testes were fixed in cacodylat-buffered 4.5% glutaraldehyde. They were cut into smaller pieces (approximately 1 mm³), post-fixed in 1% osmium tetroxide. The fixed tissues were dehydrated by passage through a graded series of ethanol, and embedded in Araldite.

Serial semithin sections were cut at approximately 1 μm thickness, stained with toluidine blue, and observed under light microscopy. Thin sections were cut for electron microscopy with glass knives with ultratome. Sections were stained with either lead citrate or double stained with uranyl acetate followed by lead citrate, and examined under a Zeiss EM-9A electron microscope.

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Figure 1: Light microscope photograph of seminiferous tubules. a: Spermatogonium b: Srimary spermatocytes c: Secunder spermatocytes d: Spermatid sh: Sertoli cells and L: Leydig cells.

Sertoli cells were tall and triangular, with cytoplasm. Cellular margins were difficult to distinguish by light microscopy. Sertoli cell nuclei were readily identified and were usually found towards the basement membrane of the seminiferous tubule. The sertoli cell nucleus was ovoid in shape with a prominent nucleolus. Sertoli cells had an extensive cytoplasm (Figure 1, 2).

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Figure 2: Light microscope photograph of seminiferous tubules. a: Spermatogonium b: Primary spermatocytes c: Spermatid sh: Sertoli cell m: Myoid cell k: Capillary.

The spermatogonia were located on or near the tubule basal lamina. It had relatively little cytoplasm. Spermatogonia were characterised by a large round or oval nucleus with condensed chromatin. Primary spermatocytes were readily recognised by their extensive cytoplasm and large nuclei. They were the largest germ cells seen within the seminiferous tubule. The spermatid was a spherical cell, and had a medium-size pale, round, or oval nucleus. The spermatozoon was an extremely elongated structure (Figure 1,2).

In the surrounding interstitial tissue, scattered large leydig cells were observed. Leydig cells were generally found singly and sometimes they were in groups in the supporting tissue. They were generally around capillaries. Leydig cell nucleus was large, round or oval with dispersed chromatin, and it was usually exantrically situated. The nuclei had a clear nuclear membrane. Leydig cells had an eosinophilic cytoplasm (Figure 1).

Transmission electron microscopy: Cytoplasm of the sertoli cell was clear. There were a number of mitochondria in their cytoplasm. They have elongated, oval and round shaped. Elongated mitochondria were striking. This represented active of sertoli cells (Figure 3).

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Figure 3: Electron microscope photograph of cytoplasm of sertoli cell. It was seen a lot of long and oval shaped mitochondria

The apical head of spermatid was entered to cytoplasm of sertoli cell and the apical head of slightly elongated spermatids was occasionally surrounded by the laminated sER (Figure 4).

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Figure 4: It was seen that the apical head of spermatid was entered to cytoplasm of sertoli cell.

Spermatogonia were characterised by a large round or oval nucleus with condensed chromatin. Granular endoplasmic reticulum was seen within the cytoplasm of spermatogonia. A number of mitochondria were also recognized. They had various shapes and sizes (Figure 5).

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Figure 5: Electron microscope photograph of spermatogonium. n: Nucleus m: Mitochondria g: Granular endoplasmic reticulum

Primary spermatocytes had a large and round nuclei. There were nuclear pores on the nuclear membrane. A well developed golgi apparatus and mitochondria were found within their cytoplasm (Figure 6).

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Figure 6: The structure of primary spermatocyte. n: Nucleus m: Mitochondria G: Golgi apparatus e: Smooth endoplasmic reticulum

The nucleus of spermatid was small and oval in shape. Mitochondria were seen in the cytoplasm of spermatid.

There were different findings about the shape of sertoli cells as pyramid ^14, columnar ³ and irregular ¹¹. In this study, the shape of sertoli cells was determined as triangular in badgers.

The present study showed that there was a lot of oval and long mitochondria in the cytoplasm of sertoli cells in the adult badgers. Similar results have been reported for human ^{3, 15} and water buffalo ¹⁶.

Leydig cells were found singly or colony of various sized cells with large and vesicular single nucleus in human (

). Leydig cells were defined as pyramidal shaped and colonized with various size around blood vessel in the adult rabbits ⁹. In rats, leydig cells were defined as irregular polygonal shaped with eosinophylic cytoplasm and large nucleus without chromatin ^{6, 7}. In this study, leydig cells were determined as generally single or rarely grouped with eosinophylic cytoplasm and large nucleus in the adult badgers.

It was reported that nuclei of leydig cells situated exantricallly in rats ⁶. We also found an eccentric nucleus in leydig cells of the adult badger.

It was reported that pig, horse and opossum have more leydig cells that occupied nearly all intertubular space ³. In this study, it was observed that leydig cells were present in intertubular areas as single or small groups in badgers.

Ross et al ¹⁵ and Leeson et al ¹⁴ reported that myoid cells composed a single layer in rodentia. However, peritubular tissue was formed by 3-5 myoid cells layer in human. Prakash et al ¹⁷ presented that myoid cells were mostly two to three layered in bonnet monkey. In the present study, it was observed that myoid cells composed only a single layer in badgers.

Jurado et al ¹⁸ found that apical head of spermatid was inserted in the cytoplasm of sertoli cell. We also determined similar result in badger.

In conclusion, light and electron microscopy examinations results of this study showed that the structure of badger's testis has many similarities with that of the other mammalian.

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