Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
2005
Volume 8
Issue 3
Topic:
Veterinary Medicine
ELECTRONIC
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Rz±sa A. , Poznański W. , Pospieszny N. , Zawada Z. 2005. NEW ASPECTS OF THE ANATOMICAL STRUCTURE OF THE SOW'S UDDER, EJPAU 8(3), #12.
Available Online: http://www.ejpau.media.pl/volume8/issue3/art-12.html

NEW ASPECTS OF THE ANATOMICAL STRUCTURE OF THE SOW'S UDDER

Anna Rz±sa1, Wiesław Poznański2, Norbert Pospieszny3, Zbigniew Zawada4
1 Department of Immunology, Pathophysiology and Veterinary Prevention, Wrocław University of Environmental and Life Sciences, Poland
2 Institute of Pig Breeding, Agricultural University of Wrocław, Poland
3 Department of Biostructure and Animal Physiology, Wrocław University of Environmental and Life Sciences, Poland
4 Department of Veterinary Anatomy and Histology, Agricultural University of Wrocław, Poland

 

ABSTRACT

The aim of this work was to advance the knowledge on the anatomical structure of the sow's udder ( glandula mammaria ) with particular reference to the number of teat glands, their distribution and size as well as the number of teat canals ( ductus papillares ) in each mammilla.

It has been found out that the number of lactiferous ducts ( ductus lactiferi ) goes together with the quality of milk production, it may also affect piglet's preferences in teat choice. It seems worthwhile to conduct selection with the view to uniforming the number of lactiferous sinus and lactiferous ducts in the sow's udder in order to achieve more uniform rearing conditions. The morphometric measurements due to their lack in the literature may be used in further research on the dynamics of swine mammary glands growth in ontogenesis.

Key words: sow?s udder, lactiferous ducts, papillary duct.

INTRODUCTION

The milk yield is one of the priority factors affecting the number and weight in reared piglets, hence many authors’ interest in the subject [4,5,7,13,16,18]. The potential milk yield depends primarily on the environmetal pressure, genetical assumptions and, consequently, structure and growth of the gland itself. In own researches [19] it has been found out that the number of lactiferous ducts ( ductus lactiferi ) goes together with the quality of milk production, it may also affect piglet's preferences in teat choice.

The formation of mammary glands commonly called teats takes place as early as the prenatal period. Their buds can be seen in both sexes as early as 23 day of fetal life in the form of geminate milk lines made up of the thickened entodermal epithelium on the abdominal side of the body. About of 60 day of fetal life the mammilla start growing. The final growth of the mammary gland takes place much later and is conditioned by sex [12]. In males it remains reduced, in females grows gradually as sexual maturity progresses. The dynamic growth of the secretive tissue occurs in the final stages of pregnancy and during lactation, to be followed by involution after piglet weaning. The changes in mammary gland transformations have a cyclic character throughout sows utilization period, however, with the growing age their intensity diminishes. In older sows numerous inflamantory changes are found which may lead to decreased local immunity of the mammary gland [14,17].

It is an often situation in the mammary gland that some parts of it develop intensively and produce milk while others become atrophied. In pigs mammary glands are situated thoracoabdominoinguinally. Extensive studies on anatomical and histological structure of milk glands in farm animals can be found in academic textbooks of, among others: Kuryszko and Zarzycki [10]; König and Liebich [8]; Najbrt and Kolektiv [15].

The aim of this work was a fuller examination of the anatomical structure of the sow's mammary gland with particular reference to number of teats (mamma), their distribution and the number of ductus papilares in each mammilla.

The results of the investigations may be practically implemented in theorethical (morphometry, comparative anatomy) and clinical sciences, breeding programmes and specially in selection criteria for breeding sows.

MATERIAL AND METHODS

Detailed evaluation involved milk glands taken from 8 pbz x wbp (polish landrace x polish large white) sows immediately after slaughter on the last day of lactation. On the farrowing day all sows were surveyed with regard to their mammary gland, in vivo determination of the number of lactiferous duct was carried out on the basis of milk flowing during milking. This procedure was applied twice at the first and second farrowing. The number of teats sucked and unsuckled was determined on the weaning day. All sows belonged to the farm's reproduction stock, were of the same age, having reared their second litter.

The corrosive preparations were made from obtained material with the use of plastic Epidian 53 introduced into lactiferous duct lumina. After its solidification and corrosion of organic components, the casts of studied glands were obtained [1].

In total 83 corrosive preparations were made, they were measured according to the Horsfield and Cumming principles [6]. The corrosive preparations were photographed with the use of a digital camera and then computer measured with the use of Lucia version 4.21 programme version. The morphometry of investigated glands was done using the electronical caliper with preciseness 0.01 mm.

The volumetric measurement of the gland was done by measuring the volumne of water forced out by particular casts of glandular systems. The area of the glands' base as an area confined by elipse of a and b semi- axises was calculated with the formula P = pab [11]. The anatomical terminology followed Anatomical Veterinary Nomenclature [2].

RESULTS

In the number of studied sows 4 had 6 mammary glands on both sides, three 7 and one 8. In total the number of teats was 106 (accessory teats were disregarded). A detailed list of mammary glands is given in Tab.I. All glands were well developed, apart from property developed teat openings (ostia papillaria), some teats exhibited additional blind ducts.

Table I. Mammary gland topography in studied sows

Gland location

Number of teats

Number of unsucked teats

Number of ductus papilares

one

two

three

thoracic

32

3

-

29

3

abdominal

56

15

1

51

4

inguinal

18

5

1

16

1

total

106

23

2

96

8

The teat openings in the thoracic part were lined one after another parallelly to the while line. It was observed that the last abdominal and inguinal teats were arranged differently, i.e. perpendicularly to that line.

In the studied material majority of glands were 2-canal ones (90.5%), 3-canal ones were much fewer (only 7.5%) and 1-canal teats occurred in 1.9% of cases.

The morphological analysis of the corrosive preparations provided many observations. The glandular tissue was loosely packed in peripheral parts in opposition to the tissue was also present there.

Table II. Mean measurements of milk glands

Teat

Teat heigh
(cm)

Area at base
(cm2)

Volumne
(ml)

P

L

P

L

P

L

1

max

min

n

5.3

6.8

4.1

8

5.2

6.4

4.3

7

234.65

287.71

208.53

8

231.92

285.91

211.57

7

440

520

400

8

430

510

400

7

2

max

min

n

5.2

7.0

4.1

7

5.4

7.3

4.1

7

264.24

292.34

215.59

7

229.59

283.71

196.41

7

420

530

400

7

410

510

410

7

3

max

min

n

5.4

6.8

4.0

6

5.4

7.0

4.2

6

229.29

273.87

184.98

6

227.99

276.71

187.23

6

380

470

350

6

360

460

370

6

4

max

min

n

5.7

7.4

4.2

5

5.6

7.2

4.3

6

227.71

262.57

182.59

5

221.05

245.79

181.52

6

340

430

310

5

360

440

310

6

5

max

min

n

5.7

7.3

4.1

5

5.7

7.3

4.3

4

201.05

251.54

176.53

5

201.36

250.67

174.05

4

350

430

310

5

340

430

310

4

6

max

min

n

5.7

7.7

4.2

4

5.8

6.1

4.5

5

142.27

186.62

129.73

4

144.44

186.42

130.05

5

320

400

290

4

330

410

290

5

7

max

min

n

6.2

7.9

4.5

6

6.2

8.1

5.3

5

138.47

157.67

119.67

6

138.00

155.71

120.29

5

320

380

300

6

325

360

290

5

8

n

6.4

1

6.2

1

137.53

1

136.59

1

290

1

300

1

P - right line; L - left line

Tab. II presents mean measurement results of specific corrosive preparations. The mammary glands had a conical shape with elliptical or circular base. The sizes of the base area and height of glands was noticeably varied. The biggest base had thoracic glands, yet in general they were shorter and fatter than the rest. The lobes building a singular mammila had similar shape and size. The only exception was found for 2 three-lobe teats in which the central lobe had a circular base while two remaining lobes of crescent-shaped bases took the teat’s circumference (Photo 1). Also among 2-canal teats some deviatious were noticed: in two teats only one lobe developed despite the presence of the second canal. In still another case a fully developed glandular system was accompanied by a second one with a very weakly developed and small glandular part (Photo 2). In both cases the glands in corrosive preparations resembled in their structure one-lobe glands. The glandular systems in the thoracic and the first and second abdominal pairs grew in the cephalad and caudad direction. In the inguen they grew laterally and medially and the last abdominal teats appeared to be a specific transitory zone. It was observed that when one gland was unsuckled then the lobes of adjoining teats grew in its direction.

Fig. 1. The corrosive preparation - 3-canal gland. ABC - glandular lobules (lobi glandulae), D - milk sinus (sinus lactiferus)

Fig. 2. 2-canal gland. A - strong expanded lobula; B,B' - rest lobules

The voluminuous asymmetry concerned lobes in one gland as well as whole glands, depending on the location. Decidedly the biggest volumne had thoracic, then abdominal and inguinal glands.

The mean morphometric measurements of particular gland elements are presented in Tab.III. The ductus papilares in all teats was a short canal of 3 to 4 mm. The pars papillaris of the sinus lactiferi had an elongated cylindrical shape (Photo 3). The glandular part (pars glandularis) was a very thin formation penetrating deeply glands’ parenchyma. On its whole length 9-14 big and 6-10 small lactiferous ducts opened into it, at angles of 360-1150. It was sometimes possible to observe tiny glandular lobules leading stright into the sinus. Most ducts in thoracic glands were situated horizontally, in one plane these ducts spread radially in all directions at an almost strightly raised upwards and lain in several layers, they grew mainly in lateral and medial directions. A great number of smaller and bigger intralobular ducts went in all directions from milk ducts (Photo 4). Glandular lobulas in all observed teats had a prism-like shape and were similar in size.

Table III. Mean morphometric measurements of gland elements

Measurements

Thoracic teats

Abdominal teats

Inguinal teats

Length of ductus papilares (mm):

max

min

3.2

4.11

2.78

3.41

4.3

2.92

3.61

4.3

3.25

Nipple part of lactiferous sinus (mm):

length

 

 

width

 

max

min

max

min

17.19

24.11

15.02

6.20

7.31

4.98

17.23

25.36

15.09

6.16

7.43

5.02

17.34

25.54

15.78

6.4

7.9

5.3

Glandular part of lactiferous sinus (mm):

length

 

 

width

 

max

min

max

min

15.43

18.21

15.02

4.67

-

-

17.23

19.02

15.11

4.52

-

-

17.78

19.7

15.31

4.58

-

-

Measurements of lactiferous ducts after separation from sinus (mm):

width

 

 

thickness

 

max

min

max

min

4.3

5.2

3.11

3.05

3.51

0.91

4.11

6.03

2.19

3.12

4.0

1.21

4.42

5.92

2.02

3.03

3.9

0.77

Angle of ducts separation from sinus (°)

max

min

86

93

75

83

98

72

69

89

54

Measurements of glandular lobules (mm):

length

 

 

width

 

max

min

max

min

7.32

11.23

4.43

5.12

6.68

2.23

6.28

10.7

3.01

5.11

6.9

2.11

7.60

12.24

3.11

5.32

6.54

1.31

Fig. 3. Medial side of mammary gland. A - glandular part of milk sinus; B - teat part of milk sinus; C - milk canal

Fig. 4. Fragment of milk take out cannals. A - milk canal; B,B' - smaller milk canals; C - interlobular canal

DISCUSSION

The anatomical structure of the sows' mammary gland is well known. The only controversial issue seems to be the number of out-leading canals. Most authors [8,15] claim that there 2 to 3 of them. Kudriawcew [9] demonstrated on the basis of corrosive preparations that there can be from 1 to 3 canals. In his studied population 51% teats were 1-canal, 7.2% 3-canal and as much as 86% 2-canal ones, 1.7% had no canals. He came to the conclusion that the quantity of milk is also affected by the number of out-leading canals in particular teats. He also claimed that this number changes depending on the location of the next teat on the udder, the closer to the inguinal area, the less teat canals. In the own research this tendency was not observed. The 2-canal glands were most numerous, the 3-canal ones could be found in all udder areas, i.e. thoracic, abdominal and inguinal ones. On the basis of own observations and contrary to Kudriawcew's results, the authors of this work are inclined to conclude that milk yield of specific glands is affected primarily by their location on the milk line and not by the number of milk canals. Similar conclusions are shared by several other authors [3,13]. Single glands location in a specific area of the udder is a very important factor limiting its growth [19]. The glands in the thoracic part have a sizeable area for free growth, in the ubdominal part there's less free room and in the inguinum the glands are additionally limited by hind legs. These facts would explain the changes of gland's shapes depending on its location.

Yet if the glands can have different number of milk canals (lactiferous ducts), the question arises as to its significance. Kudriawcew [9] reported that a decidedly higher number of teats with one milk canal occured in primiparous than multiparous sows. Such teats as less milk yielding caused earlier culling of sows due to warse rearing results. According to the same author 3-canal teats are more lactiferous than the 2-canal ones, but occur more rarely. Authors suggests that it would be worthwile to conduct selection with a uniform (as far as the number of lactiferous ducts is concerned) udder structure in view and secure relatively equal conditions for piglet development.

The quantity of produced milk does not go together with its quality and, more precisely, its immunological value; here the effect of the anatomical structure of particular teats can be observed. Sow's milk is different than in case of other species because in the whole period of lactation it contains locally produced class A immunoglobulines (SIgA). The number of lactiferous ducts goes together with the surface where these immunoglobulines can be synthetized, therefore further studies on the anatomical structure of the sow’s udder and its effect on piglet rearing results seem highly advisable and beneficiary in practical pig breeding.

Tab. 3 presents morphometric measurements of glands, which due to the lack of such data in the literature can be used in further research on the dynamics and development of porcine mammary gland in ontogenesis.

ACKNOWLEDGEMENTS

The study was supported by the research project no6PO6Z 041 21, financed by the State Committee for Scientific Research.

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Anna Rz±sa
Department of Immunology, Pathophysiology and Veterinary Prevention, Wrocław University of Environmental and Life Sciences, Poland
C.K. Norwida 31
50-375 Wrocław
Poland
email: anna.rzasa@up.wroc.pl

Wiesław Poznański
Institute of Pig Breeding,
Agricultural University of Wrocław, Poland
Chełmo?ego 38d, 51-630 Wrocław, Poland

Norbert Pospieszny
Department of Biostructure and Animal Physiology,
Wrocław University of Environmental and Life Sciences, Poland
Kożuchowska 1/3, 51-631 Wrocław, Poland

Zbigniew Zawada
Department of Veterinary Anatomy and Histology,
Agricultural University of Wrocław, Poland
Kożuchowska 1-3, 51-631 Wrocław, Poland

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