Talk:Dog Development

The IGF1 small dog haplotype is derived from Middle Eastern grey wolves http://www.biomedcentral.com/1741-7007/8/16

2010

Total neuron numbers in CA1-4 sectors of the dog hippocampus

Indian J Med Res. 2010 Jun;131:780-5.

Rağbetli MC, Aydinlioğlu A, Koyun N, Yayici R, Arslan K. Departments of Histology & Embryology , Medical Faculty, Yüzüncü Yil University,Van, Turkey. Abstract BACKGROUND & OBJECTIVES: Early reports addressed morphological asymmetry in the cross-sectional width of the rat hippocampus. The present study was aimed at counting total number of neurons in CA1-4 sectors and the subiculum of the dog hippocampus as well as investigating possible left /right and male/female asymmetry. METHODS: Adult mongrel dogs (8 female and 5 male) were assessed by the right and left pawedness and sacrificed by exsanguinations. In each hippocampus dissected, the total neuron numbers of CAs and subiculum were estimated by the physical fractioning method. RESULTS: Significant hemispheric asymmetries were found in the number of pyramidal cells of CA1, CA3/2, CA4 and the subiculum. Sex difference was also found in the subiculum, in favour of the males. INTERPRETATION & CONCLUSION: Our study indicated a left dominant asymmetry in males and right dominancy in females as well as no functional asymmetry in specific regions of the dog hippocampus. Further investigations are necessary to verify the hypothesis that hippocampal morphological asymmetries in normal subjects are functionally related in memory or in cognitive skills. PMID: 20571166

Early Development and Putative Primordial Germ Cells Characterization in Dogs

Reprod Domest Anim. 2010 Apr 30.

Martins DS, Ambrósio CE, Saraiva NZ, Wenceslau CV, Morini AC, Kerkis I, Garcia JM, Miglino MA.

Faculty of Animal Science and Food Engineering, University of Sao Paulo, Pirassununga, Brazil. Abstract Contents Previously, three distinct populations of putative primordial germ cells (PGCs), namely gonocytes, intermediate cells and pre-spermatogonia, have been described in the human foetal testis. According to our knowledge, these PGCs have not been studied in any other species. The aim of our study was to identify similar PGC populations in canine embryos. First, we develop a protocol for canine embryo isolation. Following our protocol, 15 canine embryos at 21-25 days of pregnancy were isolated by ovaryhysterectomy surgery. Our data indicate that dramatic changes occur in canine embryo development and PGCs specification between 21 to 25 days of gestation. At that moment, only two PGC populations with distinct morphology can be identified by histological analyses. Cell population 1 presented round nuclei with prominent nucleolus and a high nuclear to cytoplasm ratio, showing gonocyte morphology. Cell population 2 was often localized at the periphery of the testicular cords and presented typical features of PGC. Both germ cell populations were positively immunostained with anti-human OCT-4 antibody. However, at day 25, all cells of population 1 reacted positively with OCT-4, whereas in population 2, fewer cells were positive for this marker. These two PGCs populations present morphological features similar to gonocytes and intermediate cells from human foetal testis. It is expected that a population of pre-spermatogonia would be observed at later stages of canine foetus development. We also showed that anti-human OCT-4 antibody can be useful to identify canine PGC in vivo.

PMID: 20477984

Comparative study of Pax2 expression in glial cells in the retina and optic nerve of birds and mammals

J Comp Neurol. 2010 Jun 15;518(12):2316-33.

Stanke J, Moose HE, El-Hodiri HM, Fischer AJ. Integrated Biomedical Science Graduate Program, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA. Abstract Little is known about the expression of Pax2 in mature retina or optic nerve. Here we probed for the expression of Pax2 in late stages of embryonic development and in mature chick retina. We find two distinct Pax2 isoforms expressed by cells within the retina and optic nerve. Surprisingly, Müller glia in central regions of the retina express Pax2, and levels of expression are decreased with increasing distance from the nerve head. In Müller glia, the expression levels of Pax2 are increased by acute retinal damage or treatment with growth factors. At the optic nerve, Pax2 is expressed by peripapillary glia, at the junction of the neural retina and optic nerve head and by glia within the optic nerve. In addition, we assayed for Pax2 expression in glial cells in mammalian retinas. In mammalian retinas, unlike the case in chick retina, the Müller glia do not express Pax2. Pax2-expressing cells are found in the optic nerve and astrocytes within the mouse retina. By comparison, Pax2-positive cells are not found within the guinea pig retina; Pax2-expressing glia are confined to the optic nerve. In dog and monkey (Macaca fascicularis), Pax2 is expressed by astrocytes that are scattered across inner retinal layers and by numerous glia within the optic nerve. Interestingly, Pax2-positive glial cells are found at the peripheral edge of the dog retina, but only in older animals. We conclude that the expression of Pax2 in the vertebrate eye is restricted to retinal astrocytes, peripapillary glia, and glia within the optic nerve. Copyright 2010 Wiley-Liss, Inc. PMID: 20437530

2009

Prolonged duration of fertility of dog ova

Reprod Domest Anim. 2009 Jul;44 Suppl 2:230-3.

Tsutsui T, Takahashi F, Hori T, Kawakami E, Concannon PW.

Department of Reproduction, Nippon Veterinary and Life Science University, Musahino, Tokyo, Japan. tsutsui@nvlu.ac.jp Abstract The fertile period for natural mating in dogs extends from before ovulation until day 5 post ovulation (PO) and involves a delay in oocyte maturation until 2-3 days PO and viability of secondary oocytes for 48-60 h or more. Spermatozoa do not enter the uterus after vaginal insemination in late oestrus. Cervical closure appears to occur on average 5 days PO, but conception may occur following intrauterine artificial insemination (IUAI) up to 8 days PO. Therefore, the present study was conducted to clarify the duration of fertility of canine ova. Using IUAI at 6, 7, 8 and 9 days PO (n = 5 bitches each) conception rates were 100%, 71.4%, 37.5% and 0%, respectively, with an average litter resorption rate of 30.8%, and with mean litter sizes and times to delivery PO being 4.3 +/- 1.6 and 64.3 +/- 0.3 days, 4.0 +/- 1.4 and 66.3 +/- 0.4 days, and 2.5 and 68 days for IUAI at 6, 7 and 8 days, respectively. The high pregnancy rates with IUAI at 6 and 7 days PO confirm that many canine oocytes are fertile at 4-5 days after maturation. The high rate of resorption was presumably because of aging of ova or asynchrony between embryonic development and the intrauterine environment.

PMID: 19754575

2008

Germinal vesicle chromatin configuration and meiotic competence is related to the oocyte source in canine

Anim Reprod Sci. 2008 Jan 30;103(3-4):336-47. Epub 2006 Dec 17.

Lee HS, Yin XJ, Jin YX, Kim NH, Cho SG, Bae IH, Kong IK.

http://www.ncbi.nlm.nih.gov/pubmed/17212978

Germinal vesicle chromatin configuration GV-I - condensed filamentous chromatin clumps around the nuclear membrane GV-II - localized filamentous chromatin clumps around the nucleolus GV-III - distributed filamentous chromatin clumps in the nucleus and disappeared nucleolus GV-IV - thick clumps of condensed chromatin GV-V - a single clump of condensed chromatin

MII, apparent first polar body;

The critical period for mullerian duct regression in the dog embryo.

Biol Reprod. 1991 Oct;45(4):626-33.

Meyers-Wallen VN, Manganaro TF, Kuroda T, Concannon PW, MacLaughlin DT, Donahoe PK.

Department of Clinical Sciences, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853-6401. Abstract The embryonic period during which Mullerian duct regression and Mullerian Inhibiting Substance (MIS) secretion occur was determined in canine embryos removed from timed pregnancies (32, 36, 37, 39, 42, and 46 days gestation). Sex chromosomes of each embryo were identified in metaphase spreads prepared from fibroblast cultures. Testicular differentiation, defined by seminiferous tubule formation and the presence of Sertoli cells and Leydig cells, and the degree of Mullerian duct regression were determined by careful morphologic analysis of histologic sections of canine embryonic gonads (n = 20) and Mullerian ducts (n = 20). MIS was detected immunohistochemically in embryonic testes using avidin-biotin complex enhancement of a specific rabbit polyclonal anti-MIS antibody. Testicular differentiation was observed at 36 days gestation. The earliest evidence of Mullerian duct regression in male embryos was observed at 36 days gestation, and regression was completed by 46 days gestation. Positive staining for MIS was present in testes from 36 to 46 days (n = 9). Staining was absent in the undifferentiated testis (n = 1) at 32 days gestation and in ovaries at all ages tested (n = 10). Thus, MIS is normally present throughout the critical period for Mullerian duct regression in the embryonic male dog.

PMID: 1751638

http://www.ncbi.nlm.nih.gov/pubmed/1751638

• Testicular differentiation was observed at 36 days gestation.
• The earliest evidence of Mullerian duct regression in male embryos was observed at 36 days gestation, and regression was completed by 46 days gestation.
• Positive staining for MIS was present in testes from 36 to 46 days (n = 9).
• Staining was absent in the undifferentiated testis (n = 1) at 32 days gestation and in ovaries at all ages tested (n = 10).
• Thus, MIS is normally present throughout the critical period for Mullerian duct regression in the embryonic male dog.