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ULTRASTRUCTURAL STUDIES OF SPERMATOGENESIS IN THE ANTHOCEROTALES. I. THE BLEPHAROPLAST AND ANTERIOR MITOCHONDRION IN PHAEOCEROS LAEVIS: EARLY DEVELOPMENT
Author(s) -
Moser John W.,
Duckett Jeffrey G.,
Carothers Zane B.
Publication year - 1977
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1977.tb10800.x
Subject(s) - anatomy , biology , centriole , ultrastructure , nucleoplasm , microtubule , spermatid , nucleus , microbiology and biotechnology , sperm , botany , nucleolus
Electron microscopic examination of thin sections showed that the blepharoplast of a young spermatid of Phaeoceros consists of two side‐by‐side centrioles and an accumulation of osmiophilic, granular matrix at their proximal ends. Lying between these nearly parallel organelles is a dark‐staining body that will later disappear at the onset of flagellogenesis. For a brief period the centrioles are oriented perpendicular to the nuclear surface so that the granular matrix at their proximal ends is confluent with the nuclear envelope; furthermore, the nucleoplasm immediately in front of the centrioles becomes densely staining. The multilayered structure (MLS) develops directly under the centrioles. It comprises a band of 12 microtubules (the S 1 stratum) and three lower strata (S 2–4 ) whose constitutent lamellae are oriented at an oblique angle to the S 1 axis. While the S 1 tubules grow rearward over the nucleus which forms a beak adjacent to the posterior end of the lamellar strata, the centrioles are transformed into basal bodies with the distal growth of the axonemes and the proximal growth of the central cartwheels and lowermost triplets. The proximal ends of the basal bodies and the S 1 tubules overlying the lamellar strata are invested with osmiophilic matrix that extends down to the S 2 layer and may temporarily occlude the lamellar plates. At the onset of nuclear elongation an anterior mitochondrion becomes situated close beneath the lamellar strata which extend laterally beyond the S 1 tubules.