Introduction

Many cases of male infertility are associated with severe tail sperm abnormalities. The first reports of a syndrome characterized by stunted tails and sperm immobility was reported in rabbits₁ and in bulls₂. Electron microscopy demonstrated that the tail defect results in a blocked formation of the flagellum generating the absence of axonema and accessory fibres₃.. This syndrome was known like ‘stump defect'. Baccetti et al. described a tail defect in humans. ₄, in which sperm immobility was also due to stunted tails, but this case was mainly characterized by the presence of biflagellate stunted tails. This abnormality was then called ‘short tail' defect. Subsequently, Baccetti et al₅ reported eight human sperm cases of stunted tails, in which half of them were classified as stump defect and the other half as short tail defect. This classification was fundamentally based on two characteristics: the presence of an extremely low sperm number (11 – 19 x 10⁶ ml^-1) and biflagellate tails in ‘short tail defect'; and on the other hand, low sperm (4 – 52 x 10⁶ ml^-1) and one stunted tail in ‘stump tail defect'. To our knowledge, only two another new cases of stunted sperm tails have been further reported₆,₇. Indeed, there are not enough cases described in humans that allow classified these syndromes clearly and the origin of these shunted tails remains unknown. We report a new case of this extraordinary unusual defect in human sperm tail, which presents some peculiarities as regard to previous cases. This case will contribute to characterize these syndromes in a better way.

Case report

A 29-year-old man was presented in our reproduction department in order to be investigated of a four year primary infertility. He had no history of significant illness and neither the patient, nor anyone else in his family, had cilia respiratory diseases. His parents were not consanguineous and he had six bothers and three sisters with children. Physical examination of the patient showed no pathological findings.

Serum and sample analysis

Semen analysis

Testes analysis

Electron microscopy procedure

Results

The analyses of four semen samples showed the following results: sperm count 278 10⁶/ml (>20x10⁶/ml), 35 % (>50%) alive forms and 0% (>50%) motility. No abnormality was found in biochemical parameters in seminal plasma. The morphological analysis revealed mainly tail disturbances: Absence of flagellum: 14-16%; short tail spermatozoa: 45-64% (Fig 1); coiled tails: 12-17%; and an abnormal proportion of spermatids and spermatocytes. Normal spermatozoa were found in 11-16% (> 30%).

Figure 1

Endocrine profile was found within the normal range FSH: 6.4 (2-8 mUI/ml), LH: 7.2 (2-12 mUI/ml), T: 28 (10-35 nmol/L).

Testicular biopsy revealed impaired spermatogenesis. It was also found reduced length tail spermatozoa in the seminiferous tubules lumen with a high percentage of degenerative spermatocytes and spermatids.

Scanning electron microscopy confirmed the abnormalities observed with optic microscopy (Fig. 2), and revealed sperm heads with intact nuclei and acrosomal regions. Surprisingly, around the 10% of the stunted tails which had been evaluated had biflagellate (Fig. 3) arrangement while the other ones had uniflagellate tail.

Figure 2

Figure 3

Discussion

The semen analysed showed some, but not all the morphological defects described by Baccetti ₄,₅ for the ‘stump tail syndrome'. The spermatozoa showed a complete immobility and most of them had a reduced tail. However, it was found that the number of spermatozoa was not reduced and that the total sperm population was not affected by the extremely reduced length of the tails. Besides, in contrast to the ‘stump tail syndrome' which is characterised by the presence of only uniflagellate spermatozoa, our sample revealed the coexistence of uniflagellate and biflagellate stunted tails. Due to this observation, the morphological defect observed cannot been exactly classified either as ‘tail stump syndrome' or as ‘short tail syndrome' according to Baccetti's criteria₄,₅. To our knowledge, this is the first human sperm in which uniflagellate and biflagellate stunted tails coexist.

Our case confirms the testicular dysfunction of spermiogenesis as the origin of these kind of tail abnormalities. However the true origin of this defect remains unknown. Sperm and cilia disturbances are often reported to be associated and genetically determined; in fact, familial cases have been described in brothers₈. Conversely, our patient had no familial history, neither others cilia disturbance, nor mail infertility. Therefore, this observation would suggest the possibility of an acquired defect or mosaics of genes that determine ciliary and flagelar axonemes.

This is an atypical case stunted tail sperm which has not been previously described and more cases will be necessary to describe properly these syndromes and to elucidate their origin.

Correspondence to

Ernesto Sánchez Sánchez Avda. Juan de Mata Carriazo 6, 4º C 41018 Sevilla (Spain) ernesto@pulso.com +34-609566292