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1.
Morphologie ; 96(313): 29-39, 2012 Aug.
Article in English | MEDLINE | ID: mdl-23017838

ABSTRACT

The structure of the millipede female reproductive system is described, discussed and reviewed. The different reproductive systems of female millipedes are illustrated, some of them for the first time. The various families appear to have developed several different structures of this organ. Nevertheless, more detailed studies on the female reproductive systems, especially the changes taking place during the oogenetic cycle, are needed in all millipede orders. Only this way can it be ascertained, whether ovarian structures observed are not only a transitional phase. This was done in two millipedes, Archispirostreptus tumuliporus judaicus (Attems 1927) and Catamicrophyllum caifanum (Verhoeff 1900), where these changes were followed for a longer period of time and on a large number of specimens. The evolutionary meaning of this diversity in reproductive systems cannot be clarified at the present time, nor its significance for the survival of the such diversified forms in the Class Diplopoda.


Subject(s)
Arthropods/anatomy & histology , Animals , Arthropods/physiology , Body Weight , Female , Microscopy, Electron, Scanning , Oocytes/ultrastructure , Oogenesis , Ovary/anatomy & histology , Ovary/cytology , Ovary/growth & development , Reproduction , Seasons , Species Specificity
2.
Anat Rec (Hoboken) ; 293(10): 1738-54, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20687160

ABSTRACT

The female scorpion ovariuterus was examined in 10 scorpion species belonging to five families: Buthidae, Vaejovidae, Scorpionidae, Urodacidae, and Diplocentridae. Two main patterns of development are known in scorpions: (1) The apoikogenic type with an ovariuterus containing yolk-rich eggs housed in follicles. This type is found in many scorpion taxa (largely buthids). A peculiar case of apoikogenic ovariuterus is a "beaded" ovariuterus where most of the ova's embryogenesis takes place inside the ovariuterus rather than on pedicels situated on the external wall of the ovariuterus as in most buthids. This type is found in a few scorpion species. (2) The katoikogenic type with an ovariuterus where the embryo develops in a diverticulum composed of four parts: a stalk (pedicel), a thickened collar, a conical portion containing the ovum, and an appendix containing the oral feeding apparatus where the embryos' chelicerae grip a "teat"-like structure, described in four families: Hemiscorpiidae, Scorpionidae, Urodacidae, and Diplocentridae. There are three kinds of diverticulae: small rudimentary finger-like diverticulae, embryonic (ED) large projections, and postpartum diverticulae (PPD) empty diverticulae, which are remnants after parturition. The subject is reviewed and its bearing on reproduction in scorpions are discussed.


Subject(s)
Ovary/embryology , Scorpions/embryology , Uterus/embryology , Animal Structures/embryology , Animals , Female , Microscopy, Electron, Scanning , Oocytes/ultrastructure , Ovarian Follicle/anatomy & histology , Ovarian Follicle/ultrastructure , Scorpions/physiology
3.
J Intellect Disabil Res ; 45(Pt 5): 424-38, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11679048

ABSTRACT

The present paper reviews studies on the prevalence of visual impairment (VI) in adults with intellectual disability (ID). Every publication describes an alarming prevalence of blindness and VI. Cataract and keratoconus were common. Many cases of poor distance vision were treatable by ordinary spherical or astigmatic glasses, but few people had had such prescriptions. Elderly residents in community and institutional care often did not receive glasses for near vision. Professional assessments disclosed higher prevalences of VI than questionnaires mailed to the care personnel. The prevalence of VI increased dramatically with the severity of ID and with age. Regular professional assessment of eye disorders, visual acuity and refraction are warranted in residents in both hospital and community care.


Subject(s)
Intellectual Disability/diagnosis , Vision Disorders/diagnosis , Activities of Daily Living , Blindness , Community Health Services , Deinstitutionalization , Eyeglasses , Humans , Intellectual Disability/complications , Intellectual Disability/epidemiology , Persons with Mental Disabilities , Vision Disorders/complications , Vision Disorders/epidemiology , Vision Screening , Visual Acuity
4.
Acta Ophthalmol Scand ; 79(5): 450-4, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11594977

ABSTRACT

PURPOSE: To assess visual impairment in adults with intellectual disability after de-institutionalisation. PATIENTS: The county has a population of 385 483 persons of 18 years and older; 961 were moderately, severely or profoundly intellectually impaired (ID), 837 of them (87 %) participated in the investigation. METHODS: Visual acuity, VA: Østerberg picture charts and reduced copies for near vision could be used in 71% of the patients. Teller preferential looking procedure was applied to people who were unable to cooperate with the picture charts. When examined with picture wall chart VA 0.3-> or =0.10) was found in 10.8%, severe low vision in 1.2% (VA <0.10-> or =0.05), and blindness (VA<0.05) in 3.8%. Poor near vision (<0.3) was present in 19%. Those assessed with Teller acuity cards had poorer vision than the others. It is possible that the low values of assessment with Teller cards represent a combination of gnostic and resolution deficiencies, which means that the results of grating VA and recognition VA are non-comparable. Ophthalmic disorders: The most widespread medical condition was cerebral visual impairment, the most frequent eye disorders were optic atrophy, high myopia, cataract, and keratoconus. Refraction: Refraction was assessed in 710 persons (85%), the most prevalent cause of visual impairment was uncorrected ametropia. Hypermetropia of >+1.50 was found in 151 of 710 subjects (21%), and spectacles were used by 106 (15%); myopia <-1.0 was present in 213 individuals (30%), 95 persons (13%) had lenses <-1.0. CONCLUSION: Resettled adult people with intellectual disability have a high prevalence of treatable visual impairment. A structured scheme of referral to optometric and ophthalmological care is essential if these people are to be given the care to which they are entitled.


Subject(s)
Intellectual Disability/epidemiology , Learning Disabilities/epidemiology , Vision Disorders/epidemiology , Visually Impaired Persons/statistics & numerical data , Adult , Aged , Aged, 80 and over , Deinstitutionalization/statistics & numerical data , Denmark/epidemiology , Eye Diseases/complications , Female , Humans , Male , Middle Aged , Refraction, Ocular , Vision Disorders/etiology , Vision Disorders/rehabilitation , Vision Tests , Visual Acuity
6.
Ophthalmic Genet ; 22(4): 207-23, 2001 Dec.
Article in English | MEDLINE | ID: mdl-11803487

ABSTRACT

The Mohr-Tranebjaerg syndrome (MIM 304700) and the Jensen syndrome (MIM 311150) were previously reported as separate X-linked recessive deafness syndromes associated with progressive visual deterioration, dystonia, dementia, and psychiatric abnormalities. In the most extensively studied Norwegian family, the Mohr-Tranebjaerg syndrome was reported to be caused by a one-basepair deletion (151delT) in the deafness/dystonia peptide (DDP) gene at Xq22. This gene has been renamed TIMM8a. We identified a stop mutation (E24X) in the TIMM8a gene segregating with the disease in the original Danish family with the Jensen syndrome, which confirms that the two disorders are allelic conditions. We also report abnormal VEP examinations and neuropathological abnormalities in affected males from the two unrelated families with different mutations. The findings included neuronal cell loss in the optic nerve, retina, striate cortex, basal ganglia, and dorsal roots of the spinal cord. The demonstration of mitochondrial abnormalities in skeletal muscle biopsies in some patients is compatible with the suggestion from recent research that the TIMM8a protein is the human counterpart of an intermembrane mitochondrial transport protein, Tim8p, recently characterized in yeast. The clinical and neuropathological abnormalities associated with mutations in the TIMM8a gene support that this X-linked deafness-dystonia-optic neuropathy syndrome is an example of progressive neurodegeneration due to mutations in a nuclear gene necessary for some, yet unknown mitochondrial transport function. We recommend sequencing the TIMM8a gene, thorough ophthalmological examination, and measuring visual evoked potentials in clinically suspected male patients with either progressive hearing impairment, dystonia, or visual disability in order to establish an early diagnosis and provide appropriate genetic counselling.


Subject(s)
Deafness/genetics , Dystonia/genetics , Mitochondrial Diseases/genetics , Mutation/genetics , Optic Nerve Diseases/genetics , Proteins/genetics , Visual Cortex/pathology , X Chromosome/genetics , Adolescent , Adult , Aged , Cell Death , Child , DNA Mutational Analysis , Deafness/pathology , Dystonia/pathology , Electron Transport Complex IV/metabolism , Evoked Potentials, Visual , Female , Genes, Recessive , Genetic Linkage , Humans , Immunoenzyme Techniques , Male , Middle Aged , Mitochondrial Diseases/physiopathology , Neurons/pathology , Optic Nerve Diseases/pathology , Pedigree , Phosphopyruvate Hydratase/metabolism , Polymerase Chain Reaction , Syndrome
7.
Anat Embryol (Berl) ; 201(5): 341-8, 2000 May.
Article in English | MEDLINE | ID: mdl-10839630

ABSTRACT

Ultrastructure of cutaneous glands is described in the Australian hylid Litoria caerulea. Three main types of glands could be distinguished in both ventral and dorsal skin: mucous, serous or granular, and lipid glands. Both mucous, and to some extent, serous glands show a PAS-positive reaction. Some of the granular-serous glands react to lipid staining. In addition, a very large gland confined to the dorsal skin of the head reacts to lipid staining. Apparently more than one type of dermal gland is involved in lipid secretion. The subject of skin lipid secretion is discussed in relation to the ecophysiological adaptations of this xeric-inhabiting frog.


Subject(s)
Anura/anatomy & histology , Anura/physiology , Exocrine Glands/metabolism , Exocrine Glands/ultrastructure , Lipid Metabolism , Skin/metabolism , Skin/ultrastructure , Animals , Body Water/metabolism , Microscopy, Electron , Water Deprivation/physiology
8.
Ophthalmic Genet ; 21(1): 51-61, 2000 Mar.
Article in English | MEDLINE | ID: mdl-10779849

ABSTRACT

Six cases of Kabuki syndrome (KS) with ocular anomalies are reported and the variety of ocular features reported in the literature for this syndrome is described. Routine ocular examinations are recommended for every patient with KS because of the high proportion of ocular anomalies found in these patients, the presence of which can hamper development if not adequately addressed.


Subject(s)
Bone and Bones/abnormalities , Dermatoglyphics , Eye Diseases/complications , Facies , Growth Disorders/complications , Intellectual Disability/complications , Adolescent , Child, Preschool , Female , Humans , Infant , Male , Syndrome
9.
Eur J Morphol ; 38(2): 80-7, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10694904

ABSTRACT

Changes in glomerular numbers and volume were followed throughout five ontogenetic stages of Pelobates syriacus (Anura, Pelobatidae). The number of glomeruli increased markedly between the 2-legged and the 4-legged tadpole stages. In the post-metamorphic stages the number of glomeruli was about twice their number during the tadpole stages. Glomerular volume peaked during the 2-legged tadpole stage, when the tadpole reached its maximal size, and dropped thereafter. There is some evidence to indicate that the number of glomeruli in post-metamorphic P. syriacus increased during growth thus indicating perhaps an increase in their functional importance. The number was still lower than that reported for some other anurans, more similar to the numbers given for representative urodeles, however, the latter have considerably larger glomeruli. Two main factors appear to be involved in regulating numbers and volume of glomeruli in frogs. The ontogenetic changes during metamorphosis affect both glomerular numbers and volume, whereas post-metamorphic growth affected only the glomerular numbers.


Subject(s)
Anura/growth & development , Kidney Glomerulus/growth & development , Metamorphosis, Biological , Animals , Kidney Glomerulus/ultrastructure , Larva , Species Specificity
11.
Ann Anat ; 182(2): 171-4, 2000 Mar.
Article in English | MEDLINE | ID: mdl-10755184

ABSTRACT

The ovariuterus of the female Pandinus imperator Koch (Scorpiones; Scorpionidae), was compared in a virgin female and a female that had previously given birth at least twice (in the laboratory). The virgin female did not have any embryonic diverticulae (Ed) nor did it have any degenerated, post-partum diverticulae (Dd), whereas in the mother scorpion several Dd were clearly seen on the ovariuterus. This latter female lacked any embryonic diverticulae (Ed). The number of the Dd corresponds well with the number of juveniles in the last brood born to that female during the previous year. Based on the total number of diverticula observed, and the average known litter size, it is suggested that these long-lived scorpions are potentially able to breed at least six times during their lifetime. Since they apparently do not breed in consecutive years (as is evident from the lack of Ed in the female that had bred a year before) and perhaps only every alternate year, they are capable of breeding for 12 years. If a litter amounts to about 25 young, a female is capable of producing 150 young. As it takes about three years to mature from nymph to adult, the life expectancy in this species is therefore about 15 years, by a conservative estimate.


Subject(s)
Genitalia, Female/anatomy & histology , Ovary/anatomy & histology , Scorpions/anatomy & histology , Animals , Female , Genitalia, Female/embryology , Genitalia, Female/ultrastructure , Microscopy, Electron, Scanning , Ovary/embryology , Scorpions/embryology
12.
Anat Embryol (Berl) ; 200(6): 607-14, 1999 Dec.
Article in English | MEDLINE | ID: mdl-10592064

ABSTRACT

The stratum corneum of the epidermis of Hyperolius viridiflavus contains several replacement layers. The outer layer is covered by mucopolysaccharide secretion. H. viridiflavus in their dry phase do not moult the sloughed off layers; these remain attached to the stratum corneum. Long and slender pillar-like cells situated under the stratum corneum extend through the stratum granulosum, stratum germinativum, and the basement membrane into the dermis. These cells abound in tonofilaments. Flask-shaped cells rich in mitochondria, reaching under the stratum corneum, extend into the stratum granulosum. They show delicate, membranous infoldings in their neck-like apical part. Granule-cells, arranged in 2 or 3 layers are situated in the stratum granulosum between the stratum corneum and germinativum. The germinative cells are large and separated from each other by wide intercellular spaces. ATPase activity was localized cytochemically in the baso-lateral cell membranes bordering with the intercellular spaces under the stratum corneum.


Subject(s)
Anura/anatomy & histology , Epidermis/ultrastructure , Adenosine Triphosphatases/analysis , Adenosine Triphosphatases/metabolism , Animals , Cell Size , Epidermis/enzymology
13.
Hum Mol Genet ; 8(9): 1785-9, 1999 Sep.
Article in English | MEDLINE | ID: mdl-10441344

ABSTRACT

The Yemenite deaf-blind hypopigmentation syndrome was first observed in a Yemenite sister and brother showing cutaneous hypopigmented and hyperpigmented spots and patches, microcornea, coloboma and severe hearing loss. A second case, observed in a girl with similar skin symptoms and hearing loss but without microcornea or coloboma, was reported as a mild form of this syndrome. Here we show that a SOX10 missense mutation is responsible for the mild form, resulting in a loss of DNA binding of this transcription factor. In contrast, no SOX10 alteration could be found in the other, severe case of the Yemenite deaf-blind hypopigmentation syndrome. Based on genetic, clinical, molecular and functional data, we suggest that these two cases represent two different syndromes. Moreover, as mutations of the SOX10 transcription factor were previously described in Waardenburg-Hirschsprung disease, these results show that SOX10 mutations cause various types of neurocristopathy.


Subject(s)
DNA-Binding Proteins/genetics , High Mobility Group Proteins/genetics , Hypopigmentation/genetics , Amino Acid Sequence , Cells, Cultured , Craniofacial Abnormalities/genetics , DNA Mutational Analysis , DNA-Binding Proteins/chemistry , DNA-Binding Proteins/metabolism , High Mobility Group Proteins/chemistry , Host Cell Factor C1 , Humans , Models, Molecular , Molecular Sequence Data , Nuclear Proteins/analysis , Octamer Transcription Factor-1 , Polymorphism, Single-Stranded Conformational , Protein Binding/genetics , Protein Structure, Tertiary , SOXE Transcription Factors , Syndrome , Transcription Factors/genetics , Transcription Factors/metabolism , Yemen
14.
Acta Ophthalmol Scand ; 76(1): 2-5, 1998 Feb.
Article in English | MEDLINE | ID: mdl-9541427

ABSTRACT

Genetic heterogeneity in ophthalmology adds a new dimension to differential diagnosis and prognosis. The indispensable clinical classification is refined by molecular genetic strategies. They sometimes build up new families of diseases, sometimes indicate that what was thought to be aetiologically related disorders are caused by different genetic mechanisms. Heterogeneity throws new light on embryological pathways, and the molecular genetics of the eye increases the information of the localisation of metabolically active substances and structural proteins in the eye.


Subject(s)
Eye Diseases/diagnosis , Eye Diseases/genetics , Eye/embryology , Genetic Heterogeneity , Diagnosis, Differential , Genotype , Humans , Molecular Biology , Ophthalmology , Phenotype
15.
Ann Anat ; 179(4): 341-7, 1997 Aug.
Article in English | MEDLINE | ID: mdl-9272218

ABSTRACT

The ultrastructure of the ventral epidermis is described in the aquatic and terrestrial phases of the newt Triturus vittatus (Jenyns). In both phases, the stratum corneum is characterized by a large number of keratinocytes and bundles of tonofilaments. Mitochondria-rich flask cells were found in both phases. The main difference was found in the abundant tuberculi on the surface, and in the number of stratum corneum replacement layers found in the terrestrial phase. The epidermis of the aquatic phase did not show any resemblance to the aquatic larval stage, thus no Leydig cells could be found.


Subject(s)
Epidermis/ultrastructure , Skin/ultrastructure , Triturus/anatomy & histology , Acclimatization , Animals , Epidermal Cells , Microscopy, Electron , Microscopy, Electron, Scanning , Mitochondria/ultrastructure , Skin/cytology , Triturus/physiology
16.
Gen Comp Endocrinol ; 106(3): 356-60, 1997 Jun.
Article in English | MEDLINE | ID: mdl-9204369

ABSTRACT

Gonadal steroid levels were determined in the ovary of Salamandra salamandra infraimmaculata during the reproductive cycle in populations from a xeric region in northern Israel. Varying proportions of previtellogenic and vitellogenic oocytes were present throughout the year, and mature oocytes were present in winter and spring. The numbers of mature oocytes were greater between December and April, after parturition. The levels of 17 beta-estradiol and testosterone rose during oocyte vitellogenesis and maturation. Levels of progesterone and 17 alpha-hydroxy progesterone appeared to be related to the level of vitellogenesis. Gravid females contained greater quantities of all four steroids than did nongravid females.


Subject(s)
Gonadal Steroid Hormones/metabolism , Ovary/metabolism , Reproduction/physiology , Salamandra/metabolism , 17-alpha-Hydroxyprogesterone/metabolism , Animals , Estradiol/metabolism , Female , Oogenesis , Progesterone/metabolism , Salamandra/physiology , Seasons , Testosterone/metabolism , Vitellogenesis/physiology
17.
Genomics ; 41(1): 93-9, 1997 Apr 01.
Article in English | MEDLINE | ID: mdl-9126487

ABSTRACT

Bardet-Biedl syndrome (BBS) is a clinically and genetically heterogeneous autosomal recessive disorder characterized by retinitis pigmentosa, polydactyly, obesity, hypogenitalism, mental retardation, and renal anomalies. To detect linkage to BBS loci, 29 BBS families, of mixed but predominantly European ethnic origin, were typed with 37 microsatellite markers on chromosomes 2, 3, 11, 15, 16, and 17. The results show that an estimated 36-56% of the families are linked to the 11q13 chromosomal site (BBS1) previously described by M. Leppert et al. (1994, Nature Genet. 7, 108-112), with the gene order cen-D11S480-5 cM-BBS1-3 cM-D11S913/D11S987-qter. A further 32-35% of the families are linked to the BBS4 locus, reported by R. Carmi et al. (1995, Hum. Mol. Genet. 4, 9-13) in chromosomal region 15q22.3-q23, with the gene order cen-D15S125-5 cM-BBS4-2 cM-D15S131/D15S204-qter. Three consanguineous BBS families are homozygous for three adjacent chromosome 15 markers, consistent with identity by descent for this region. In one of these families haplotype analysis supports a localization for BBS4 between D15S131 and D15S114, a distance of about 2 cM. Weak evidence of linkage to the 16q21 (BBS2) region reported by A. E. Kwitek-Black et al. (1993, Nature Genet. 5, 392-396) was observed in 24-27% of families with the gene order cen-D16S408-2 cM-BBS2-5 cM-D16S400. A fourth group of families, estimated at 8%, are unlinked to all three of the above loci, showing that at least one other BBS locus remains to be found. No evidence of linkage was found to markers on chromosome 3, corresponding to the BBS3 locus, reported by V. C. Sheffield et al. (1994, Hum. Mol. Genet. 3, 1331-1335), or on chromosome 2 or 17, arguing against the involvement of a BBS locus in a patient with a t(2;17) translocation.


Subject(s)
Abnormalities, Multiple/genetics , Chromosomes, Human, Pair 11/genetics , Chromosomes, Human, Pair 15/genetics , Chromosomes, Human, Pair 16/genetics , Genetic Linkage , Chromosome Mapping , Female , Genes, Recessive , Genetic Markers , Haplotypes , Humans , Hypogonadism/genetics , Intellectual Disability/genetics , Lod Score , Male , Obesity/genetics , Pedigree , Polydactyly/genetics , Retinitis Pigmentosa/genetics , Syndrome
18.
Ann Anat ; 179(1): 57-64, 1997 Feb.
Article in English | MEDLINE | ID: mdl-9059741

ABSTRACT

The gill epithelium ultrastructure of the larval stage of the newt, Triturus vittatus, has been studied. Two layers can be distinguished: an outer layer and an inner layer. The outer layer is composed of four cell types: pavement cells, ciliary cells, mitochondria-rich cells (MRC) and round, granule-containing cells. Large numbers of vesicles containing PAS (+) material can be seen in the apical part of the pavement cells. Their outer face is covered with short microvilli. The ciliary cells contain many mitochondria and their surface is adorned with cilia. The mitochondria-rich cells are fully packed with mitochondria. They are unique in having elaborate tubular membranous infoldings, which open on to the surface in a net-like arrangement of long, slender microvilli. Finally, the outer layer contains very few (29 cells in a 35 mm length tissue, or 0.8/1 mm) rounded, granule-containing cells. These granules, of various sizes and shapes, are PAS (-) and contain elaborate Golgi figures. The inner layer is characterized by the presence of numerous, large Leydig cells; 19.56 cells/mm tissue. Finally, large, germinative cells rich in tonofilaments are situated on the basement membrane.


Subject(s)
Gills/ultrastructure , Triturus/anatomy & histology , Animals , Epithelial Cells , Microscopy, Electron , Microscopy, Electron, Scanning
19.
Oecologia ; 112(3): 314-319, 1997 Oct.
Article in English | MEDLINE | ID: mdl-28307478

ABSTRACT

The objective of this study was to associate levels of nutritional reserves (specifically lipids, sugars, and glycogen) in individual Mediterranean fruit flies, Ceratitis capitata (Diptera: Tephritidae), with observed patterns of behavior in the field. We collected females (n=255) and males (n=181) from the field, recording the time of collection and the activity they were engaged in when collected. Subsequently, we employed colorimetric biochemical techniques to determine the precise amounts of lipids, sugars, and glycogen in each individual. Lipid and sugar levels in males varied significantly according to the time of collection and the type of activity. Lipid and sugar levels in females did not vary in this manner. Sugar levels in both males and females were highest during the evening, when most feeding occurs. Males that engaged in sexual signaling in leks during the mid-afternoon had relatively low sugar and high lipid levels. Males engaged in the alternative mating tactic of fruit guarding had relatively high sugar and low lipid contents. Glycogen levels in males were high in the mornings, and a decline in glycogen content was associated with participation in leks; however, female glycogen levels did not vary significantly with time of day or activity. Our results provide quantitative evidence for the role nutrient reserves play in driving patterns of male reproductive behavior, yet suggest that factors other than sugar and lipid reserves constrain female behavior.

20.
J Morphol ; 231(2): 149-160, 1997 Feb.
Article in English | MEDLINE | ID: mdl-29852615

ABSTRACT

Reproductive cycle and oogenesis were studied in specimens of Salamandra salamandra infraimmaculata Mertens that inhabit fringe areas of the taxon's distribution in the Mediterranean region. Both ovarian mass and length are correlated significantly with body mass and length. Ovarian length is also correlated with the number of oocytes. During the oogenetic cycle six stages in oocyte development were recognized. Three occur during previtellogenesis: stage 1, in which oogonia divide and form cell nests; stage 2 in which oogonia differentiate into oocytes; and stage 3, in which the oocyte cytoplasm increases in volume. In the vitellogenic phase two additional stages, 4 and 5, were recognized: stage 4, in which lipid accumulates in vacuoles in the periphery followed by the appearance of yolk platelets near the cytoplasmic margin; and stage 5, in which oocyte volume increases rapidly due to increased number of yolk platelets until it reaches its maximal size. During postvitellogenesis one stage was recognized: stage 6, in which the beginning of maturation is characterized by movement of the nucleus toward the animal pole. Oogenesis continues year-round. The first four stages were seen in all ovaries examined. The ovarian cycle is independent of season and reproductive stage apart from the number of mature, postvitellogenic oocytes that increases following gestation toward the beginning of spring (March-April). J. Morphol 231:149-160, 1997. © 1997 Wiley-Liss, Inc.

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